AL 8
The late Professor E. A. Minchin, M.A., F.R.S.
Frontispiece]
[See page 669
THE JOURNAL
OF THE
(fyukttk
Microscopical Club
EDITED BY
A. W. SHEPPARD, F.Z.S., F.R.M.S.
SECOND SERIES.
VOLUME XII.
1913-1915.
.»»»»--».._
••...••••
[Published for the Club]
WILLIAMS AND NORGATE,
14. Henrietta Street, Covent Garden. London,
and 7, Broad Street, Oxford.
PRINTED BY
HAZELL, WATSON AND VIXEY, LD.,
LONDON' AND AYLESBURY.
Ill
C O N T E N T S .
PART No. 72. APRIL 1913.
Papers.
E. Heron-Allen. F.L.S., F.R.M.S., awl A. Euiland, F.R.M.S.
The Foraminifera in their Role as World- builders : A
Review of the Foraminiferous Liiw stones and Other Rocks
of th^ Eastern and Western Hemispheres (Plates 1-3)
W. M. Bale, F.R.M.S. Notes on Some of the Discoid Diatoms .
Henry Whitehead, B.Sc. Some Notes on British Freshwater
Rhabdocoelida — a Group of Turbellaria (Plate 4)
Charles F. Rousselet, F.R.M.S. The Rotifera of Devils Lake,
with Description of a New Brachionus (Plates 5 and (3)
Arthur Dendy, D.Sc, F.R.S. President's Address— By- Pro-
ducts of Organic Evolution (Plate 7) .
David Bryce. On Five New Species of Bdelloid Rotifera (Plates
8 and 9) ........
Notes.
E. M. Nelson, F.R.M.S. A New Low-power Condenser
E. M. Nelson. F.R.M.S. Xavicula rhomboides and Allied Forms
E. M. Nelson, F.R.M.S. On Microscope Construction and the
Side Screw Fine Adjustment (Figs. 1 and 2 in text)
E. M. Nelson, F.R.M.S. Note on Pleurosiqma angukitum (Figs.
3 and 4 in text) ........
E. M. Nelson, F.R.M.S. Actinoci/clus Ralfsii and a Coloured
Coma .... .....
Notices or Books ........
PAGH
1
17
4.3
57
05
83
95
90
90
98
100
101
Proceedings, etc.
Proceedings from October 22nd, 1912, to February 25th, 1913,
inclusive .........
Forty-seventh Annual Report, 1912 r
Report of the Treasurer. 1912 .
103
113
120
PART No. 73, NOVEMBER 1913.
Papers.
E. Heron-Allen, F.L.S., F.G.S., F.R.M.S., and A. Earland,
F.R.M.S. On some Foraminifera from the North Sea,
dredged by the Fisheries Cruiser " Huxley " (International
North Sea Investigations — England) (Plates 10 and 11) .
12 1
'\J
■ ■-
IV CONTENTS.
PACK
C. D. Soar, F.L.S., F.R.M.S. Description of Arrhenurus Scour-
fieldi and Acercus longitarsus, Two New Species of Water-
mites (Plates 12 and 13) 130
G. T. Harris. The Collection and Preservation of the Hydroida 143
T. A. O'Donohoe. The Minute Structure of Coscinodiscus
asteromphalus and of the Two Species of Pleurosigma,
P. angulatum and P. balticum . . . . .155
Henry Sidebottom. Lagenae of the South-West Pacific Ocean
(Supplementary Paper). (Plates 15-18) . . .101
James Murray, F.R.S.E. Gastrotricha (Plate 19) . . 211
Notes.
Edward M. Nelson, F.R.M.S. On a New Method of Measuring
the Magnifying Power of a Microscope . . ,239
Proceedings, etc.
Proceedings from March 25th, 1913, to June 24th, 1913 . 245
Obituary Notice : Rt. Hon. Sir Ford North, F.R.S., F.R.M.S. . 258
PART No. 74. APRIL 1914.
Papers.
Arthur Dendy, D.Sc, F.R.S. President's Address — Organisms
and Origins ........ 259
S. C. Akehurst, F.R.M.S. A Changer for Use with Sub-stage
Condensers (Figs. 1 and 2) . . . . . .277
S. C. Akehurst, F.R.M.S. A Trap for Free-swimming Or-
ganisms (Fig. 3) . . . . . . . . 279
E. M. Nelson, F.R.M.S. An Improved Form of Cheshire's
Apertometer (Fig. 4) . . . . . . .281
F. J. Cheshire, F.R.M.S. Two Simple Apertometers for Dry
Lenses (Figs. 5 and 6) ..... . 283
M. A. Ainslie, R.N.. B.A., F.R.A.S. A Variation of Cheshire's
Apertometer (Figs. 7 and 8) . . . . . 287
James Burton. On the Disc-like Termination of the Flagellum
of some Euglenae . . . . . . 29 J
E. M. Nelson, F.R.M.S. On the Measurement of the Initial
Magnifying Powers of Objectives (Fig. 9) . . . 295
S. C. Akehurst, F.R.M.S. Some Observations concerning Sub-
stage Illumination (Plates 20-22) . . . .301
T. A. O'Donohoe. An Attempt to Resolve and Photograph
Pinnularia nobilis ....... 309
N. E. Brown, A.L.S. Some Notes on the Structure of Diatoms
(Plate 23) 317.
Notes.
James Burton. On a Method of Marking a Given Object for
Future Reference on a Mounted Slide. . . .311
CONTENTS. V
Vk v.
}). M. DRAPER. A Live Box for the Observation of Insects and
Similar Objects ........ 313
15. M. Draper. Dark-ground Illumination with the Greenough
Binocular ......••• 313
E. M. Nelson. F.R.M.S. Amphvpleura Lindheimeri . . 315
Notices of Books ........ 339
Proceedings, etc.
Proceedings from October 2Sth, 1013, to February 24th. 1914.
inclusive ......... 340
Forty-eighth Annual Report, 1913 314
Report of the Treasurer, 1913 302
List of Members . ...... i — xxxii
PART No. 75. NOVEMBER 1914.
Papers.
Edward M. Nelson. F.R.M.S. A New Object Glass by Zeiss.
and a New Method of Illumination (Figs. 1-3) . . . 3
Edward M. Nelson. F.R.M.S. A New Low-power Condenser
(Fig. 4) 367
Edward M. Nelsox. F.R.M.S. Binocular Microscopes (Fig. 5) . 309
A. E. Hilton. Notes on the Cultivation of Plasmodia of Badhamia
utricularis (Fig. 0) ...... 381
A. A. C. Eliot Merlin, F.R.M.S. On the Minimum Visible . 385
C. F. Rousselet, F.R.M.S. Remarks on Two Species of African
Volvox 393
C. F. Rousselet, F.R.M.S. Report on the Conference of Dele-
gates of Corresponding Societies (British Association) held
at Havre ......... 395
( '. F. Rousselet, F.R.M.S. Pedalion ou Pedalia ; une question
de nomenclature dans la classe des Rotiferes . . .397
Proceedings, etc.
Additions to the Library since January 1914 . . . 399
Additions to the Club Cabinet since October 1912 ... . 401
Proceedings from March 24th to June 23rd. 1914, inclusive . 411
Obituary Notice : Dr. M. C. Cooke 422
Table for the Conversion of English and Metrical Measures . . 424
PART No. 76, APRIL 1915.
Papers.
R. T. Lewis. F.R.M.S. The Early History of the Quekett
Microscopical Club . . . . . . 42 ~>
D. J. Scourfield. F.Z.S., F.R.M.S. A New Copepod found in
Water from Hollows on Tree Trunks. (Plates 24 and 25) 431
VI CONTENTS.
PAGE
E. A. Minchin, M.A., F.R.S. Some Details in the Anatomy of the
Rat Flea (Ceratophyllus fasciatus). (Plates 26-32) . .441
Arthur Dendy, D.Sc., F.R.S. President's Address. The Bio-
logical Conception of Individuality .... 465
W. Williamson, F.R.S.E., and Charles D. Soar. F.L.S.,
F.R.M.S. British Hydracarina : The Genus Lebertia.
(Plates 33 and 34) 479
J. W. Gordon. A " New " Object Glass by Zeiss (Figs. 1 and 2) 515
G. T. Harris. Microscopical Methods in Bryological Work . 52 !
Proceedings, etc.
Proceedings from October 27th, 1914, to February 23rd, 1915,
inclusive . . . . . . . . .537
Forty- ninth Annual Report, 1914 . . . . . .551
Report of the Treasurer, 1914 . . . . . . 558
Obituary Notice : F. W. Millett, F.G.S., F.R.M.S. . . . 559
PART No. 77, NOVEMBER 1915.
Papers.
M. A. Ainslie, R.N., B.A., F.R.A.S. An Addition to the Ob-
jective (Figs. 1 and 2) ..... 561
A. A. C. Eliot Merlin, F.R.M.S. Notes on Diatom Structure . 577
G. T. Harris. A Note on the Slides of Fissidentaceae in the
Q.M.C. Cabinet 581
A. E. Hilton. Further Notes on the Cultivation of Plasmodia
of Badhamia utricularis ...... 585
James Burton. Hydrodictyon reticulation .... 587
E. M. Nelson, F.R.M.S. Various Insect Structures . . . 593
J. W. Evans, D.Sc, LL.B. (London). The Determination of
Minerals under the Microscope by means of their Optical
Characters (Plates 35-37) 597
David Bryce. On Five New Species of the Genus Habrotrocha
(Plates 38 and 39) 631
Notices of Books (Plate 40) ...... 643
Proceedings, etc.
The Club Cabinet, Additions to . . . . .646
Proceedings from March 23rd to June 22nd, inclusive . . 653
Obituary Notice : E. A. Minchin, M.A., F.R.S. (Portrait) . 669
Index to Volume XII. . . . . . . . 673
Vll
LIST OF ILLUSTRATIONS.
PLATES.
Portrait of the late Prof. E. A. Minchin. M.A., F.R.S., Facing page 501
1-3. Foraminiferal Limestones.
4. Rhabdocoelida.
5. Asplanchna Silvestrii Daday.
6. Rotifera.
7. Spicules of Tetraxonid Sponges.
8, 9. New Species of Bdelloid Rotifera.
10. Foraminifera from the North Sea.
11. Cornuspira diffusa Heron- Allen and Earland. Sand Grains,
etc., from the Bottom Deposits.
12. <$ Arrhenurus Scour fieldi sp. nov.
13. q Acercus longitarsus sp. nov.
14. Structure of Pleurosigma bait ten m.
15-18. Lagenae of the South-West Pacific Ocean.
19. Gastrotricha.
20. View of Back Lens of Objective with P. angulatum in focus.
21, 22. Resolution with Annular Illumination.
23. Structure of Diatoms.
24, 25. Moraria arboricola sp. nov.
26-32. Anatomy of the Rat Flea.
33, 34. The Genus Lebertia.
35-37. Examination of Minerals.
38, 39. Xew Species of Habrotrocha.
40. Rhizopoda.
FIGURES IN THE TEXT.
Page 98. Side-screw fine adjustment.
,, 99. Upper and lower membranes in P. strigusum and P. balti-
cum.
„ 277. A changer for sub-stage condensers.
,, 280. A trap for free- swimming organisms.
,, 281. An improved form of Cheshire's Apertometer.
,, 285. Two simple apertometers for dry lenses.
VJ11 LIST OF ILLUSTRATIONS.
Page 288. A variation of Cheshire's Apertometer.
-j8J. ,, ,, ,,
298. The measurement of the initial magnifying power : diagram
to show relative position of apparatus.
32Q. Structure of pores in P. balticum according to O. Miiller.
365. Diagram showing method of illumination.
oOO. ,, ,, ,, ,,
3C8. Centring stop-holder.
374. Diagram of eye and Ram~den disc.
383. Exhibition of plasmodia.
517. Diagram illustrating a " new " object-glass.
"10' »J »? ?» »>
567. An addition to the objective : diagram.
504. Various insect structures.
-3
THE JOURNAL : V
OF THE
<®iuhcii $$t c rose opt cal dDInIr«
THE FORAMINIFERA IN THEIR ROLE AS WORLD-
BUILDERS: A REVIEW OF THE FORAMINIFEROUS
LIMESTONES AND OTHER ROCKS OF THE
EASTERN AND WESTERN HEMISPHERES.
By Edward Heron-Allen, F.L.S., F.R.M.S., axd
Arthur Earland, F.R.M.S.
{Read October 22nd, 1912.)
Plates 1-3.
" Life , as we call it, is nothing but the edge of the boundless Ocean of
Existence where it comes on Soundings." — 0. W. Holmes, The Pro-
fessor, V.
Our late President, Prof. E. A. Minchin, F.R.S., in his last
Presidential Address * dealt with certain organisms which he
regarded as the simplest existing living structures, and speculated
on the Origin of Life in this planet. Subsequently at the British
Association Meeting at Dundee he led a most interesting dis-
cussion on the same subject, a discussion which left those who
had the privilege of listening to it convinced of one fact at least,
viz. that no two of the eminent men who took part in the debate
were agreed on any single point. But as the earliest forms
of life were necessarily of such a simple nature that they could
oy no possibility have been preserved as fossils, the interest
of geologists may almost be said to commence with the stage
in which life had become endowed with a sufficiently complex
structure to leave recognisable remains in the geological record.
The Foraminifera would seem to constitute such a group. Of
extremely simple structure, mere protoplasm without differenti-
ation other than the nucleus, they yet possess the power either
of secreting a solid shell from the mineral salts absorbed from
* Journ. Q.M.C., Ser. 2, Vol. XI. p. 339.
Jourx. Q. M. C, Series II.— No. 72. 1
*)
E. IIIRON-ALLEN AND A. EARLAND ON THE FORAMINIFERA
their surrounding medium, or'of building up adventitious shells
by the co-ordination of foreign material obtained from their
immediate environment. These shells, from their minute size
and composition, are peculiarly adapted for preservation as
fossils.
Hence, whatever the origin of life may have been, we might
reasonably expect that among its earliest records would occur
Foraminifera of simple and ancestral types, and that subsequent
geological periods would show a constant progression in their
development. Such, however, is not the case. So far as our
geological knowledge carries us at present, the Foraminifera
make their first appearance in the rocks in a highly differentiated
stage, and among the earliest recognisable groups are many species-
which are still existing and dominant types to-day.
It is not so very many years, less than half a century in fact,
since the sensational discovery of Eozoon Canadense (1) (2) (3) in
the Laurentian rocks of Canada was hailed as evidence that the
oldest fossil was, as might have been expected, a rhizopod. Into
the long warfare which was waged round this fossil, in which the
late Prof. K. Mobius took an active part (22), it is not proposed
to enter in detail. But there was at the time of its discovery
no greater authority on the Rhizopoda than the late Dr. W. B.
Carpenter, a former President of this Club. He threw the whole
weight of his authority into the scale in favour of the foramini-
feral nature of Eozoon, and to the last was convinced of the
soundness of his belief. But the balance of evidence has turned
against him, and since his death but little interest has been
shown in the question, Eozoon having been relegated by more or
less general consent to the mineral kingdom.
We are, however, again threatened with a renewal of the
controversy, for Mr. It. Kirkpatrick, of the British Museum,
has recently announced in Nature that he is in possession of
fresh evidence of the foraminiferal nature of Eozoon, and will
shortly publish it. The microscopical world will no doubt await
this evidence with interest, not unmixed, perhaps, with some
trepidation at the reopening of this chose jugee. From the point
of view of the subject of our paper, viz. " The Foraminifera as
World-builders," definite proof of the rhizopodal nature of
Eozoon would be very welcome. Eozoon, whatever its nature
may be, occurs in enormous reefs in the Laurentian rocks of
IN THEIR ROLE AS WORLD-BUILDERS. 3
Canada and elsewhere, and we should thus have evidence that
even at this early stage of the world's history, the Foraminifera
had commenced to play that important part in the formation
of strata which they have continued in nearly all the successive
periods of geological history, and which is still proceeding in
the deep sea to-day. It is no exaggeration to say that, in
spite of their diminutive size, the Foraminifera have played,
and are still playing, a greater part in building up the crust
of the earth than all other organisms combined.
Dismissing Eozoon for the present as incertae sedis, we find
that the only other pre-Cambrian records which can be associated
with Foraminifera are the peculiar bodies described by Cayeux (4)
from certain quartzites and pthanites of the pre-Cambrian strata
of Brittany. These are, however, of such minute size compared
with other Foraminifera that their nature cannot be accepted
on the evidence hitherto available.
It appears, therefore, that at present we have no unquestionable
records of Foraminifera in pre-Cambrian rocks ; but it is quite
possible that such discoveries may be made in the future, as fossils
of a higher type have been found, and it seems unlikely that
Foraminifera did not, or could not, exist in seas capable of
supporting such higher forms of life.
When, however, we come to the Cambrian strata we find the
Foraminifera flourishing, and already marked by numerous widely
separated types. So long ago as 1858 Ehrenberg (5) figured
some internal glauconitic casts of Foraminifera from a clay near
St. Petersburg, which is known to be of Lower Cambrian age.
According to Chapman (9) these casts are referable to at least
five genera, viz. Verneuilina and Bolivina (family Textularidae),
Nodosaria (family Lagenidae), Pidvinulina and Rotalia (family
Rotalidae).
Now it is noteworthy that none of these genera are of simple
or primitive types, but are all comparatively complex in the
arrangement of their chambers, and representing three distinct
types of construction. Hence in this earliest geological record
we find the group already well established, and markedly
differentiated in structure. No monothalamous or primitive
type appears in this earliest list, although we may be sure
that they must have been in existence, both then and during
antecedent ages.
4 E HERON-ALLEN AND A. EARLAND ON THE FORAMTNIFERA
Since the time of Ehrenberg there have been other discoveries
of Cambrian Foraminifera in America (6) (7) and Siberia (8).
We have not had an opportunity of seeing either of these reports,
but it may be noted that the New Brunswick rocks furnished
representatives of the pelagic genera Orbulina and Globigerina
(family Globigerinidae), while the Siberian rock is described as
•assuming an oolitic structure on account of the numerous Fora-
minifera which it contains. It is therefore apparent that the
Foraminifera had already assumed that dominant position which
they have ever since maintained in the biology of the sea.
Turning to our own country, the oldest Foraminifera yet
recorded are those described by Chapman (9) from a limestone
of Upper Cambrian age near Malvern (PI. 1, fig. 1). This record is
'of great interest because all the Foraminifera described are either
monothalamous (genera Lagena, SpiriUina) or polythalamous
shells of simple type (genera Nodosaria, Marginulina, Cristel-
laria). As will be seen from the rock section figured by Chapman,
the Foraminifera of one genus, SpiriUina, form a considerable
proportion of the entire mass of the rock (PI. 1, fig. 1). The other
species described are stated to have been of very rare occurrence.
Now SpiriUina is one of the simplest conceivable types of rhizo-
podal shell structure, an undivided tube coiled on itself in one plane,
iand is theoretically one of the forms which might be expected
to turn up in the earliest records. Chapman has on certain
minor points of structure instituted a new species {SpiriUina
«Groomii Chapman) for this Cambrian type, but it appears to
be nothing more than a variety of SpiriUina vivipara Ehrenberg,
a species which at the present day occurs on muddy bottoms
of moderate depth in all parts of the world.* So far as we
are aware, however, there is no other record of its occurrence
in sufficient abundance to form a noticeable constituent of any
deposit, recent or fossil. In recent dredgings it cannot be
described as an abundant species.
In the next period, the Silurian, there are many records (10)
(11) (12) (13) of Foraminifera, but they do not appear to be
numerous. Brady (12) records and figures four species of the
* Since this was written specimens resembling SpiriUina Groomii (Chap-
man) have been found in dredgings made in Blacksod Bay, Co. Mayo, and
also in the Moray Firth. They will be described and figured in the
forthcoming report on the Foraminifera of the Clare Island Survey.
IN THEIR ROLE AS WORLD-BUILDERS. 5>
simple type Lagena, which are still existing, and of world-wide
distribution. These and the Spirillina Groomii of Chapman
(= S. vivipara Ehrenberg) are therefore probably the oldest
living types now in existence.
Of greater interest is the recording by Chapman (14) and
Vine (15) of two genera of arenaceous Foraminifera, viz. Hyperam-
mina and Stacheia from rocks of the Wenlock series. These
constitute, so far as we are aware, the earliest evidence of the
existence of arenaceous Foraminifera. The geological record
does not furnish any evidence in support of the theory, so fre-
quently postulated, that the earliest Foraminifera were types
Avith adventitiously constructed tests \ nor do we see any reason
for accepting this theory. The property of secreting mineral
salts from the surrounding medium is common to organisms of
all grades, whereas the power of selecting and utilising foreign
material seems to indicate a later and higher stage of develop-
ment. There appears to be no geological reason why the
composite tests of arenaceous Foraminifera should have escaped
fossilisation, when the delicate shells of -calcareous genera were
preserved, had the two groups been in existence together in pre-
Silurian times.
The Devonian period, according to Chapman (16), presents
but a single record of Foraminifera, viz. those discovered by
Terquem (13) at Paffrath in the Eiffel. Chapman comments
on the singular absence of Foraminifera in the Devonian seas,
where the conditions for their existence appear to have been
favourable.
With the next period, however, the Carboniferous, the Fora-
minifera first begin to justify the title of our paper as Worldr
builders. Various genera make their appearance in such
numbers as to form enormous deposits. In the lower Carbonif-
erous strata the large arenaceous species known as Saccammina
fusuliniformis (McCoy) = S. Carteri (Brady) (17) is the principal
constituent of enormous areas of limestone in Great Britain and on
the Continent (PI. 1, fig. 2). The upper Carboniferous limestone,
on the other hand, is in most regions of the world largely built up
of the shells of Fusulina, a perforate foraminifer belonging to
the family Nummulinidae. Other genera which are largely
concerned; in the formation of Carboniferous limestones are
'Endothyra\i^\. 1, fig. '6) and Archaediscus, while in this period
6 E. HERON-ALLEN AND A. EARLAND ON THE FORAMINIFERA
occur the first records of two genera, Amphistegi?ia and Nura-
mulites, which in later times were destined to play an important
part in the formation of the world's crust.
The Permian and Permo-Carboniferous rocks show a decline
in the importance of the Foraminifera. Perhaps it would be
more correct to say that there is a falling off in the records of
those large and dominant types which marked the Carboniferous
period. Foraminifera of many different genera occur in the
Permo-Carboniferous rocks, but they are usually of compara-
tively small size, and so do not readily form a basis for rock
formation. But in New South Wales and Tasmania, Nubecularia,
which is the lowest type of imperforate foraminifer, forms a
principal constituent of some limestones (18) (PL 1, fig. 4).
TheTrias yields no strata in which Foraminifera are the principal
constituent. Foraminifera occur in many horizons, but do not
constitute any large proportion of the fauna. Perhaps the
richest deposit is that described by Chapman (19) from Wedmore
in Somerset.
Similarly in the Jurassic period, the Foraminifera, although
often varied and abundant, are not responsible for any important
proportion of the whole bulk of the formation. They are often
confined to limited zones, in which they occur in great abundance,
but the species are nearly all minute and completely masked as
to external appearance by other material. The most important
feature of this period, however, is the sudden bursting into active
existence of numerous hyaline types, principally Lagenidae,
hitherto more or less unknown. They occur in the clays of the
Lias of the Continent in enormous variety, passing insensibly
from one species into another, and the meticulous precision of
Terquem and others who have monographed these strata has
embarrassed the rhizopodist with a wealth of synonyms.
Up to this period the arenaceous Foraminifera have not presented
any great diversity of forms, although, as we have seen, certain
genera (Saccammina, Endothyra, etc.), have played an important
part in building up strata. But Haeusler (20) (21) has de-
scribed a most interesting series of arenaceous types from a
sandy marl of Jurassic (Oxfordian) age in the Canton of Aargau
(Switzerland), which includes many genera now known to us
only from deep water. It is altogether one of the most pro-
nounced and characteristic rhizopodal faunas recorded in the
IN THEIR ROLE AS WORLD-BUILDERS. 7
fossil condition. The occurrence of this rich series of genera,
some of which appear to be confined to this formation while
others are hardly known except in the recent condition, suggests
that the arenaceous foraminifera have, with few exceptions, always
been confined to the deep sea, and that their scanty geological
history may be due to that fact, and to the rarity of ancient deep-
sea deposits.
Passing to the Cretaceous period, we find the Neocomian and
Aptian strata comparatively devoid of recognisable foraminiferal
remains. But it is almost certain that Foraminifera of the
smaller types existed in enormous numbers in the seas of these
periods, leaving their evidence behind them in the shape of the
glauconitic casts and grains which bulk so largely in the Green-
sands.
The Gault of England and the Continent contains a rich and
varied foraminiferal fauna running into several hundred species.
But although the Rhizopoda must have swarmed in the Gault
seas, they do not constitute any large percentage of the total
mass of the formation, and are often confined to limited zones.
The same remark may be applied to the numerous beds of
•chalk ranging from the Chalk Marl to the Upper Chalk. It is
one of those popular beliefs which die so hard that chalk is made
up entirely of the shells of the Foraminifera, and the textbooks
and microscopical works abound with statements to that effect.
Some of the methods suggested to students for the obtaining of
specimens can only have originated in the fertile brains of the
authors. The beginner is instructed to obtain a lump of chalk
and scrub it to fragments with a toothbrush under water ; or to
place some lumps in a bag and smash them up with a hammer,
subsequently kneading the mass under a tap until the water runs
away clear. It is needless to say that such methods can never
produce anything but debris and disappointment. These methods,
together with directions for the adequate preparation of chalk
material for examination, have been fully discussed by Heron-
Allen in his " Prolegomena " (23).
There are very few zones in the Chalk which do not contain
Foraminifera, but their number is as a rule small compared with
the whole bulk of amorphous matter. But it is probable that
in the Chalk sea the Foraminifera really abounded, and
that the amorphous carbonate of lime is derived largely from
8 E. HERON-ALLEN AND A. EARLAND ON THE FORAMINIFERA
their comminuted and dissolved remains subsequently reprecipi-
tated.
Certain zones of the Chalk, notably the zones of Holaster planus
and Micrdster, yield Foraruinifera in larger numbers, but even
here a section of the rock will show their limited distribution^
The bulk of the organic remains will be found to consist of small
spherical bodies which when cut in section show as rings (PI. 2r
fig. 1). These, the so-called " Spheres " of the chalk, are perhaps-
the origin of the belief that chalk is built up of the shells of
Foraminifera. But whatever the " Spheres " may be, we are
convinced that they are not Foraminifera. Their nature is still
in doubt, although they have been relegated in turn to the
Foraminifera, the Radiolaria and the Diatomaceae. Mr. W..
Hill, F.G.S., of Hitchin, whose knowledge of the microscopic
structure of chalk is unrivalled, and who has devoted many years-
to the study of these " Spheres," has published a scheme for the
division of the Chalk into zones, based on their occurrence and
numbers (32), but he is still unable to explain their origin and
nature. We suggest that they may be the chitinous tests
Of flagellate infusoria such as are found in great numbers in the
sea to-day, of practically identical size and shape.
The Chalk of Maestricht is rich in Foraminifera, and may
be regarded as the starting-point of the rich Foraminiferal
fauna of the Tertiary period, as it contains many large generar
OrbiioliUs, Operculina, Orbitoides, etc.> which reached a maxi-
mum of development and distribution in Eocene and Miocene
times.
Passing into Tertiary times we reach the Golden Age of the
Foraminifera; the age in which they were to reach their
maximum development both as regards size and abundance, and
to leave their remains in great beds extending across whole
continents, and often of an enormous thickness.
These Tertiary Foraminifera are very sparingly represented
in Great Britain. The London clay, although it contains a rich
rhizopodal fauna in a limited zone, is on the whole absolutely
barren, and the Thanet Sands and Woolwich and Beading beds
have yielded few records.
In the Bracklesham beds of Hampshire, however, we find a
zone almost entirely composed of two or three species of Nummu-
lites. At Selsey Bill the foreshore at low tide, on the east shore,
IN THEIR ROLE AS WORLD-BUILDERS. 0
is for a large area covered with an exposure of this zone (the-
41 Park " beds), and one cannot walk without crushing vast
agglomerated masses of Nummulites laevigatas, extending for
miles and occupying broad areas between tide-marks.
Off the extremity of Selsey Bill lies the extensive reef known
as "The Mixon." It is exposed at low tide, and is then found
to be a limestone principally composed of one species of fora-
minifer, Alveolina Boscii Def ranee. Other species (notably a large
alveoliniform Jliliolina, Nummulites, and a large Polymorphina)
are to be found in the rock, but this is dominant (PL 2, fig. 2).
Alveolina Boscii, which has built up enormous areas of limestone
extending across Southern Europe to the Himalayas, is still in
existence to-day, and is now forming similar deposits off many-
tropical shores. The Selsey specimens — the only ones to be found
in Great Britain — are indistinguishable from those to be dredged
in shallow water to-day, off the Great Barrier Reef of Queensland
and in many other places (24).
At Stubbington and its neighbourhood, in Hampshire, smaller
types of Nummulites, viz. Nummulites elegans and JV. variolariar
are to be found in similar abundance.
Turning to the Continent, we find these Nummulitic and
Alveoline limestones developed to an incredible extent. With
interruptions here and there, they spread in a broad band across-
Europe, Asia and Northern Africa to the Himalayas, attaining
in many places a thickness of several thousand feet (PI. 2, fig. 3).
The species vary with the zone and locality, but, as a rule, the-
whole rock is built up of their more or less perfect remains, and
undeft the microscope the very debris in the interstices of perfect
specimens is found to consist of their comminuted remains-
(Pl. 2, fig. 4 and PI. 3, fig. 1).
Among the more familiar instances of Nummulitic limestone-
may be mentioned the Pyramids of Egypt, which are built of
limestone quarried in the neighbouring Mokattam Hills, largely
composed of a single species of Nummulite — N. Gizehensis (Ehren-
berg). We illustrate in Plate 3, fig. 1 a section through a micro-
spheric specimen of this Nummulite, one of a series collected for us
by Mrs. A. M. King, F.R.M.S. The peculiarity of these remains
struck the geographer Strabo, who accounts for their presence in
the limestone by asserting that they were the petrified remains
of lentils from the rations of the ancients who built the
10 E. HERON-ALLEN AND A. EARLAND ON THE FORAMINIFERA
Pyramids.* They are to this day known locally as " Pharaoh's
beans." t
Philip de la Harpe begins his Monograph on the genus (27)
with the words, " Egypt is the classic land of the Nummulites,"
and Dr. Carpenter in his Introduction (28) passes in review the
legends which have attached themselves to this organism, from
Herodotus (?), Pliny (?) and Strabo to the learned Clusius, who
refers to " the popular belief of the Transylvanians that they
were pieces of money turned into stone by King Ladislaus, in
order to prevent his soldiers from stopping to collect them just
when they were putting the Tartars to flight ! " J
Tt may be remarked that Prof. Haug has suggested (31)
abolishing the Lyellian nomenclature of geological periods for all
epochs later than the Cretaceous, and the redistribution of the
strata into Nummulitic, Neogene, and Quaternary. He suggests
that the Nummulitic, whose classification is founded solely upon
this foraminifer alone, shall be divided into the Eo-Nummulitic,
which will comprise the Montian, the Thanetian, and the Lon-
■donian (names which speak for themselves), the Meso-Nummu-
litic, which will comprise the Lutetian and Ludian, and the
Neo-Nummulitic, which includes all strata from the Lower
Oligocene up to the dawn of the Glacial Period — which com-
mences his Quaternary.
As a rule these two dominant types, Alveolina and Nummulites,
* Strabo, Geographica, lib. xvii. cap. i. §34: cpaal d'airoXidudrji'a.i \el\pava
tt?s rdv epya^ofxtvocv rpocprjs. ovk direoiKe. See the note on this passage in
Canon Rawlinson's translation (1860).
f In spite of the fact that Herodotus (who has been credited with
Strabo's observation on the Nummulites) expressly states (Euterpe, IT. § 37)
that the Egyptians never grew or ate beans in any form.
X Clusius (i.e. Charles de l'Ecluse, 1526-1609), in Caroli Clusii et aliorum
vpistolae, Paris (Epistola xxxvii.), thus records the matter : " Intellexi item
genus quoddam lapillorum planorum et quasi circino in orbem ductorum
inveniri in montibus qui Pannoniam a Daciasive Transilvania disterminant,
quorum alii auri, alii argenti colorem referunt et characteribus insigniti
videntur sed incognitis. Ferunt Ladislaum regem quum Tartaros praeda et
spoliis onustos persequeretur atque metueret, ne militum suorum avaritia
■et ignavia, qui thesauris per viam stratis ab hostibus inhaerebant, victoria
illi e manibus eriperetur, a Deo petiisse ut nummi illi et pecunia ab hosti-
bus in via relicta in lapides mutarentur, quo militem sic delusum alacriorem
haberet in persequendo hoste." A passage contemporary with, if it should
not precede, Mr. C. D. Sherborn's earliest reference to Conrad Gesner
(1566).
IN THEIR ROLE AS WORLD-BUILDERS. 11
do not exist together, but the transition from one dominant to
the other is often quite sharp. We show a section from Sherani,
on the N.W. frontier of India, illustrating the junction of the
two beds. Within a thickness of two inches the rock turns from
a Nummulitic to an Alveoline limestone (PI. 3, fig. 2). What
possible explanation can there be for such a radical and cata-
clysmic change, necessitating the practical extinction of one
dominant, and the sudden rise to prominence of another, widely
■different, type? It cannot be a case of evolution, as the two
species represent entirely different types of structure.
With the passing of the Eocene period the Foraminifera lose
their all-important position as rock-builders. Through Oligocene
and Miocene times they continued to flourish, and to form
•deposits largely or entirely built up of their remains. The genus
-Nummulites dies out, dies so completely that at the present day
it is represented by only a single small species of rare occurrence
in tropical seas. Alveolina persists, but no longer as a dominant.
Orbitoides, a highly specialised type which had made its first
■appearance in the Chalk of Maestricht, attains sudden abundance
and forms great beds of Orbitoidal limestone in all the Con-
tinents, only to die out absolutely in the Miocene (PI. 3, fig. 3).
But the Miocene and later Tertiary deposits, though often
presenting an abundant and extremely varied foraminiferal
fauna, no longer owe their existence to the occurrence of one or
iew species in enormous numbers, except in those comparatively
few deep-sea deposits which have been raised to the surface
in the West Indies, New Guinea and the Pacific, and which
are similar in structure and often in species to the deposits
which are being found in the deep sea to-day (25) (26) (PI. 3,
&s-i]- . ....
Perhaps the conditions under which foraminiferal life exists
to-day may help to explain the change. We have now no seas
-swarming with Nummulites and Alveolina, to the practical
■exclusion of other species Here and there about the world the
shallow-water Foraminifera are to be found in such .profusion
that, given favourable means of preservation, we should have in
time a true foraminiferal limestone. From the shallow waters of
the West Indian seas we have received dredgings almost entirely
composed of the genera Orbiculina and Miliolina. In the shallow
lagoons of the Pacific Tinoporus baculatus, Alveolina Boscii and
12 E. HERON-ALLEN AND A. EARLAND ON THE FORAMINIFERA
Orbitolites complanata still form banks which impede navigation.
But speaking generally, the activity of the Foraminifera to-day
is displayed in another sphere. In the surface waters of the
great oceans the few genera which are found in the pelagic-
condition swarm in countless numbers, and their dead shells
falling constantly to the sea floor, are there building up layers of
Globigerina ooze which, if solidified and raised to the surface,,
would be visible as areas of foraminiferal limestone exceeding
even the Nummulitic limestones in extent.
Murray and Renard estimate the area of sea bottom over
which Globigerina ooze is at present in process of formation at
over 49 1 million square miles. Of its depth we can, of course,,
form no idea, but as the great oceans are practically permanent,,
it must be very great, because we know from deep-sea deposits
which have been elevated into land surfaces in Malta, Barbados,.
Trinidad and Australasia, that similar deposits have been forming
in the deep sea ever since at least Miocene times. ■
Prof. Agassiz has observed (29) : "No lithological distinction
of any value has been established between the chalk proper and
the calcareous mud of the Atlantic," and it has been reasonably
postulated by Prof. Jukes-Brown (30), after a careful analysis
of calcareous oozes, that the chalk was deposited in a sea of less
than 500 fathoms, though doubtless at a considerable distance
from land. The time occupied in the deposit of the English
chalk, arguing by the rate at which the Atlantic ooze is
formed, which is one foot in a century, must have been
150,000 years.
We cannot but feel that this paper has already overpassed the
reasonable limits of such a communication, but our difficulty has
been mainly one of selection. The matter is one whose ramifi-
cations are almost infinite. A systematic study of the dynamics
of the subject remains yet to be completed, though significant
beginnings have been made by Prof. Hull and by Prof. Jukes-
Brown. A careful consideration of the factors which have led
to the deposition of certain forms of Foraminifera and other
microzoa in an orderly sequence, dependent for the most part
upon current action and specific gravity, must lead us to an
understanding of the forces which have accounted for the
Building of the World in the form in which we know it. And
it is by the study* of such factors, as revealed by their results,
IN THEIR RuLE AS WORLD-BUILDERS. 13
that geologists have been able to reconstruct the geographical
features of ages inconceivably remote.
Bibliography.
1. Dawson, J. W. On the Structure of Certain Organic
Remains in the Laurentian Limestones of Canada. Quart.
Journ. Geol. Soc, 1865, p. 51, pi. vi., vii.
2. Carpenter, W. B. Additional Note on the Structure and
Affinities of Eozoon Canadense. Quart. Journ. Geol. Soc,
1865, p. 59, pi. viii., ix.
3. Ibid. On the Structure, Affinities and Geological Position of
Eozoon Canadense. Intellectual Observer, No. XI., p. 278.
2 plates.
4. Cayeux, L. Sur la Presence de Restes de Foraminiferes dans
les Terrains precambriens de Bretagne. Ann. Soc. Geol.
Xord., 1894, vol. xxii., pp. 116-19.
5. Ehrexberg, C. G. Ueber andere massenhafte mikroskopische
Lebensformen der altesten silurischen Grauwacken-Thone
bei Petersburg. Sitzungs. phys.-math. Kl. Monatsb. Ak.
Wiss., Berlin, 1858, p. 324, pi. i.
6. Matthew, W. D. On Phosphate Nodules from the Cambrian
of Southern New Brunswick. Trans. New York Acad.
Science, 1893, vol. xii., pp. 108-20 and pi. i.-iv.
7. Matthew, G. F. The Protolenus Fauna. Trans. New York
Acad. Science, 1895, vol. xiv., pp. 109-11, pi. i.
S. De Lapparent, A. Traite de Geologie, 4th ed., 1900, Paris,
p. 790.
9. Chapman, F. Foraminifera from an Upper Cambrian
Horizon in the Malverns. Quart. Journ. Geol. Soc, 1900,
pp. 257-63, pi. xv.
10. Keeping, W. On some remains of Plants, Foraminifera and
Annelida in the Silurian Rocks of Central Wales. Geo-
logical Magazine, 1882 ; Dec. II., vol ix., p. 490.
11. Blake, J. F. Lower Silurian Foraminifera. Geological
Magazine, 1876, N.S. (Dec. II.), vol. iii., p. 134.
12. Brady, H. B. Note on some Silurian Lagenae. Geological
Magazine, 1888, pp. 481-84.
13. Terquem, O. Observations sur quelques fossiles des
Epoques Primaires. Bull. Soc. Geol. France, Ser. 3 (1880),
vol. viii., pp. 414-18, and pi. xi.
14 E. HERON-ALLEN AND A. EARLAND ON THE FORAMINIFERA
14. Chapman, F. On some Fossils of Wenlock Age from Mulder
near Klinteberg, Gotland. Ann. Mag. Nat. Hist., 1901r
pp. 141-60, pi. iii.
15. Vine, G. R. Notes on the Annelida tubicola of the Wenlock
Shales from the washings of Mr. G. Maw, F.G.S. Quart,
Journ. Geol. Soc, vol. 32 (1882), p. 390. See also
F. Chapman, Ann. Mag. Nat. Hist., 1895, Ser. VI.,.
vol. xvi., p. 311.
16. Chapman, F. The Foraminifera. London, 1902, p. 255.
17. Ibid. Note on the specific name of the Saccammina of the
Carboniferous Limestone. Ann. Mag. Nat. Hist., 1898,
Ser. 7, vol i., pp. 216-18.
18. Chapman, F., and Howchin, W. A monograph of the
Foraminifera of the Permo-Carboniferous Limestones of
New South Wales. Mem. Geol. Survey, New South Wales,
1905. Palaeontology, No. 14, p. 5.
19. Chapman, F. On some Foraminifera of Rhaetic Age from
Wedmore, in Somerset. Ann. Mag. Nat. Hist., 1895r
Ser. 6, vol. xvi., pp. 305-29, 2 plates.
20. Haeusler, P. Die Astrorhiziden und Lituoliden der
Bimammatus-zone. Neues Jahrb. filr Min., 1883, vol. i.r
pp. 55-61, pi. iii., iv.
21. Ibid. Monographie der Foraminiferen der Transversarius-
Zone. Abhandl. Schiveiz. Paldont. Gesellsch., 1891,,
vol. xvii., pp. 1-135, 15 plates.
22. Mobius, K. Der Bau der Eozoon Canadense nach einigen
Untersuchungen vergleichen mit dem Bau der Foramini-
feren. Cassel, 1878.
23. Heron-Allen, E. Prolegomena towards the study of the
Chalk Foraminifera. London, 1894, pp. 10-14.
24. Heron-Allen, E., and Earland, A. The Recent and Fossil
Foraminifera of the Shore-sands at Selsey Bill, Sussex.
Journ. R. Micr. Soc, 1908, p. 529; 1909, pp. 306, 422r
677 ; 1910, pp. 401, 693 ; 1911, pp. 298, 436.
25. Schubert, P. Die fossilen Foraminiferen der Bismarck-
archipels und einiger angrenzender Inseln. K. K. Geo-
logischen lieichsanstalt, vol. xx. Part 4. Vienna, 1911.
26. Jukes-Brown, A. J., and Harrison, J. B. The Geology of
Barbados. Part II. The Oceanic Deposits. Quart.
Joarn. Geol. Soc, 1892, vol 48, p. 170.
IN THEIR ROLE AS WORLD-BUILDERS. 15
27. La Harpe, P. de. Monographie der in Aegypten und der
libyschen Wiiste vorkommenden Nummuliten. Palaeonto-
graphica, vol. xxx. 1883 (3 Folge, Bd. 36), p. 155.
28. Carpenter, W. B., Parker, W. K., Jones, T. B. Intro-
duction to the study of the Foraminifera. London (Ray
Soc), 1852, p. 262.
29. Agassiz, A. Three Cruises of the Blake. London, 1888,.
vol. i., p. 150.
30. Jukes-Brown, A. J. Handbook of Physical Geology.
London, 1884, p. 130.
31. Haug, E. Traitede Geologic II. Les Periodes Geologiques.
Fascicule 3. Paris, 1911.
32. Jukes-Brown, A. J. The Cretaceous Bocks of Britain, with
contributions by W. Hill. London, Geological Survey,
volii., 1903, vol. iii., 1904.
Description of Plates 1 — 3.
With the exception of PI. 1, fig. 1, PI. 3, fig. 4, the figures are
from original sources.
Plate 1.
Fig. 1. Spirillina Limestone. Upper Cambrian, Malvern (after
Chapman, Q.J.G.S., vol. lvi., 1900, Plate 15).
,, 2. Saccammina Limestone. Carboniferous. Pathhead, Had-
dington, N.B.
,, 3. Endothyra Limestone. Carboniferous. Indiana.
„ 4. Nubecularia Limestone. Permo- carboniferous. Polkolbin,
Maitland, N. S. Wales.
Plate 2.
Fig. 1. Middle Chalk. Zone of Rhynchonella Cuvieri. Hitchin.
,, 2. Alveolina Limestone. Eocene. Mixon Bock, Selsey.
,, 3. Alveolina Limestone. Eocene. Bunnu, N. W. Frontier
India.
, 4. Kummulitic Limestone. Eocene. Gizehj Egypt.
16 E. HERON-ALLEN AND A. EARLAND ON THE FORAMINIFERA.
Plate 3.
Fig. 1. Nummulites Gizehensis (Ehrenberg), microspheric speci-
men. Horizontal section, through primordial chamber.
„ 2. Alveolina and Nummulitic Limestone. Eocene. Shiranni,
N. W. Frontier, India, showing the junction of the
two beds.
3. Orbitoidal Limestone. Miocene. Japan.
4. Globigerina Limestone. Miocene. Bismarck Archipelago,
Pacific (after Schubert, loc. cit., Plate 5, fig. 4).
Jourii. Quekett MicroscopicabClub, Ser. 2, Vol. XIL, No. 72, April 1913.
Journ. Q.M.C.
Ser. 2, Vol. XII., PI. 1
3 4
Fo RAM IN I FERAL LIMESTONES.
Journ. Q.M.C.
Ser. 2, Vol. XII., PI. 2.
FoRAMINIFERAL LIMESTONES.
Journ. Q.M.C.
Ser. 2, Vol. XIL, PL 3.
3 4
FORAMINIFERAL LIMESTONES.
17
NOTES ON SOME OF THE DISCOID DIATOMS.
By W. M. Bale, F.R.M.S.
(Contributed by Prof. A. Bendy, January 2Sth, 1913.)
In the following notes, written for the most part several years
since, I have attempted, in somewhat desultory fashion, a survey
of some of the principal characters which have been utilised in
the discrimination of species in three or four of the best-known
genera of discoid diatoms. Some of the conclusions at which I
have arrived as to the inadequacy of many of these distinctions
have, I am aware, been reached by previous observers, more
especially in the genus Coscinodiscus ; but in such cases the
special instances now brought forward may perhaps be service-
able in reinforcing those conclusions. In other cases, particularly
in the genus Actinoptychus, my observations tend to prove that
characters accepted as specific even by recent authors are de-
monstrably unreliable. I have not pursued my investigations
more fully, as I have found the subject too difficult, owing to the
impossibility of procuring much of the literature, and to my total
isolation from other observers. I trust, however, that these notes
may not be without interest for students of the Diatomaceae,
and that the suggestions therein may be of some value to those
who occupy themselves with their classification.
Coscinodiscus. — Notwithstanding all that has been done to-
wards the elucidation of this unwieldy genus, it still remains the
most difficult — as it is the most extensive — of the whole order.
This follows naturally from the general similarity of form, and
the absence in most cases of any specialised areas or conspicuous
appendages such as serve to distinguish the species in Actin-
cptychus, A uliscus, etc. Many forms which have been described as
Journ. Q. M. C, Series II. — No. 72. 2
18 W. M. BALE ON SOME OF THE DISCOID DIATOMS.
distinct differ only in having the markings a little smaller or
larger, while others are characterised by trifling distinctions of
detail which, on examination of an extended series of specimens,
are found to break down utterly. On the other hand it will be
seen that, in many instances, details which might be helpful in
the discrimination of species have been generally overlooked.
The first serious attempt to grapple with the difficulties
involved in the classification of the genus was that of Grunow,.
in his work on the Diatoms of Franz-Josef Land, a perusal of
which leads one to regret that this acute observer did not carry
out a more comprehensive survey of the whole genus. Rattray's
Revision, though giving evidence of a vast amount of painstaking
research, is far from final in regard to the species admitted,
many of which are characterised by features obviously not of
specific — sometimes not even of varietal — value. Moreover, in
working over slides from well-known deposits, one finds many
forms which it is impossible to place under any of the species
described, though it is most unlikely that Rattray could have
failed to observe them. The impression is produced that many
of the descriptions have been framed on particular specimens,,
without any allowance for the range of variation usually present.
The "key" is minimised in value owing to the use in many of
the sections of characters which are quite inconstant, or which
may characterise the type but not the varieties, while the attempt
to include all the sections in one key has added much to the
difficulty of the undertaking, and has involved mistakes which
render it in some cases quite unreliable. (As an example, let
the observer take a typical valve of C. asteromphalus and attempt-
to trace it through the key, and he will fail to find it. But it
appears under Section 116, and, if followed backwards, it will
be referred to Section 111, where the description is, "Markings
rounded, granular ; interspaces hyaline, unequal, rows radial,"
which obviously cannot apply to the species at all.)
Nevertheless Rattray's work undoubtedly represents a great
advance in its suppression of a large number of pseudo-species,
though one cannot but regret that the process has not been
carried further.
Mr. Cox, going to the opposite extreme, would reduce all the
multitudinous forms of Coscinodiscus to seven species, Actinocyclus
Ehrenbergii being included as one of them. Some diatomists
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 19
have expressed approval of this proposal, but none have adopted
it, nor are any likely to do so.
In surveying the various characters by which species may be
defined, the outline will naturally be the first to be considered.
This in the Coscinodisci, however, is of little assistance, as, except
in a few aberrant species, the circular form prevails. Passing to
the surface contour, we have a character which has been utilised
by Grunow, Rattray, and others, but by no means so fully as
might be. Thus neither of these observers, in differentiating
C. asteromphalus from C. centralis, refers to the fact that the
former has usually the centre depressed, while the latter is
convex throughout. In several cases the absence of information
on this point in Rattray's descriptions just renders the diagnosis
doubtful. And this is the more important from the fact that
even a good figure does not always bring out this special point.
At the same time it may be observed that it is not rare for
individuals of a given species to depart from the normal character
in regard to surface contour, and further, that in particular
localities this variation may prevail. This refers especially to a
tendency for the surface to be more depressed than is normally
the case, and does not apply to C oscinodiscus only. Thus in some
of the Oamaru deposits we find that Aulacodiscus margaritaceus,
A. amoenus and the large forms of the Triceratium favus group
are all characterised by the unusually depressed surface of the
valves.
It may be noted, further, that it is not safe to describe the
surface contour of a species without examining both valves.
Rattray describes C. superbus as convex, but in reality one valve
is convex, while the other has the centre depressed. Several
species, such as C. tumidus, have the surface concentrically undu-
lated, while in a series of forms, described by Grunow as Pseudo-
Stephanodiscus, there is an asymmetrical inflation of the surface.
The inflations and depressions in C. excavatus are also familiar
examples of specialised areas.
Variations of the radial symmetry, other than those men-
tioned, are rare. A notable instance is that of C. cocconeiformis,
which has the markings bilaterally arranged.
In the great majority of cases the form, size and arrangement
of the cellules or puncta which cover the surface are the prin-
cipal or sole ground relied upon for specific distinction, many
20 W. M. BALE ON SOME OF THE DISCOID DIATOMS.
so-called species being differentiated solely by slight variations in
the size of the areolation, or by its increasing or decreasing
in size towards the margin. All such species, unless other and
weightier differences can be found, should be swept aside as
spurious. The same remark applies to the presence or absence
of a central area, of a central rosette of larger areolae, of
bright points at the origin of the shorter radial series, of parts
of the surface where the polygonal areolation is replaced by
separate circular cellules, and of fine punctate secondary markings.
Any of these characters may, of course, be constantly associated
with a particular species; but, in many species at any rate,
examination of a sufficient series readily shows that they may be
indifferently present or not. Indeed, within the limits of the
single species C. asteromphalus a range of forms may be found
some or other of which exhibit every one of the characters just
mentioned, while others show none of them.
In some respects the size of the valve (i.e. with reference to
the average of the species) is a determining factor in the
arrangement of the markings. Thus in such forms of C. radiatus
as are usually considered typical there are commonly three or
four slightly larger cellules in the centre, and the rest are in
distinctly radial series. In smaller valves the central cellules
are no longer than the rest, and in the smallest forms the radial
disposition of the cellules is totally lost. A still more striking
instance is found in one of the robust forms of C. asteromphalus,
common in some of the North American deposits. The largest
valves have a conspicuous central rosette of large cellules, and
outside these the areolae are much smaller, gradually increasing
in size, however, to the mid-radius. With a diminution in the
size of the valve comes a modification in the direction of levelling
down the differences in size of the areolation — the rosette-cells
become smaller, and those next to them larger in proportion.
One stage in this series is the C. biangulatus of Schmidt, which
is only a normal form of this group, and by no means of specific
or even varietal value. In the smallest forms of the series all
trace of the rosette is wanting, the areolae are fairly uniform in
size throughout, and the centre of the valve is not depressed as
in larger specimens, but convex or very slightly flattened, while
in many valves the cellules are separate and circular on part of
the surface, as in C. perforatus and C. apiculatus. Similarly the
-I
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 21
C. crassus, so abundant in the Sendai deposit, simply consists of
the smaller valves of the equally abundant G. borealis, to which
• it bears the same relationship that C. biangulatus does to
C. asteromphalus.
In C. marginatus the small valves, with uniform and non-
radial areolation, are considered typical, but, as in the above-
mentioned species, we find that valves of maximum size have the
areolation distinctly radial, with the areolae increasing in size
from the central rosette towards the margin.
In other species similar conditions occur, indicating that the
reduction of the differences in size of the areolae is the regular
concomitant of the reduction in size of the valves, and showing
how little such variations are to be relied on as specific
distinctions.
The presence of a central area may be of specific value in
some instances, but in many species it is quite worthless even as
a varietal character. Sometimes its disappearance is due to the
cellules surrounding it becoming enlarged at its expense. Thus
in C. perforatus and C. apiculatus normal valves (if indeed wo
are right in considering as normal those valves with separate
round markings, which I greatly doubt) have a blank central
space, and the cellules surrounding it are in no way different
from the rest, but when, by the enlarging of the cellules-
generally at the expense of the intervening substance, the
structure becomes areolate, the most central cellules often
enlarge inwards till they obliterate the area, and thus form a
rosette, as in C. Oculus Iridis, etc.
Far too much importance has been attached to the area in
Rattray's monograph, especially in the key.
The central rosette is one of the most variable of characters.
In some cases, as already mentioned, it is conspicuous in the
largest valves, dwindling and finally vanishing in the smaller
ones ; in others, just alluded to, it results from the obliteration,
entire or partial, of the central area. In some no doubt it
may be regarded as a fairly constant specific character.
The tendency in some species for the polygonal areolation to
be replaced on a portion of the valve by isolated circular cellules
may be briefly referred to. C. perforatus and C. apiculatus are
familiar cases in which this modification occurs, either over the
whole surface of the valve, or on more or less of one side, while
22 W. M. BALE ON .SOME OF THE DISCOID DIATOMS.
in C. gigas, G. diorama, and a few others, it is the central part
of the valve which is so modified. Though in C. apiculatus and
C. perforat us it is universally recognised that this peculiarity is
not of specific importance, the loose disposition of the markings
in the central part of such species as C. diorama has been made
use of to characterise the species, but in some cases at least
unwarrantably. In a species found in Port Phillip the larger
valves have the markings as in G. diorama, while the smaller
ones are areolate throughout. When the modification in question
occurs in the central part of a valve it is usually associated with
a thinner condition of the silex, but this does not appear to be
the case in such species as G. perforatus and G. apiculatus.
In rare cases the loosely disposed and rounded markings occur
on an annular area, concentric with the margin, and an interest-
ing example of this is found in the large, robust form of G. Oculus
Iridis found in the Mors deposit. It is a variable form as regards
the surface contour, but commonly in large valves the centre and
the sub-marginal zone are about equally elevated, and the inter-
vening broad annular area is slightly depressed. A varietal
form differs in having this depression much deeper, and, on the
outer side, very abrupt, while in a third form the annular
depression is very deep and narrow, and on the bottom of the
depression the cellules are rounded and separate (a condition to
which there is sometimes a tendency in the second form). This
last variety was described by Grunow in his work on the diatoms
of Franz-Josef Land as a new species, under the name of
G. annidatus, notwithstanding which it was figured later on
PI. 184 of Schmidt's Atlas under the name of Craspedodiscus
Molleri.
I have also seen a form of G. excavatus, very near to Grunow' s
var. semilunaris, in which there is a complete annular depression,
with round markings, not far from the centre.
The circular areas of the varieties just mentioned, as well as
the inflations of ordinary forms of G. excavatus, are all instances
of abrupt bulging in (or out) of the substance of the valve, and
in all of them the portion which is subject to this bulging
appears thinner than the rest of the valve, while the markings
are fainter, as well as being rounded and loosely disposed.
The occurrence of " bright points " at the origin of the shorter
radial series of cellules has been commonly regarded as a valid
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 23
specific character. In some instances these " bright points " are
merely the optical expression of a local thickening of the silex ;
more generally, however, they are true cellules, differing from the
rest in their minute size. They are conspicuous in C. perforatus,
and they form the principal ground of distinction between that
species and C. apiculatus. But in examining a large series of
€. perforatus var. ceilulosa I find them by no means so constant
as to justify the importance attached to them. While in some
valves they appear at the origin of all, or nearly all, the shorter
rows of areolae, in others they are much sparser, and in a few
cases I failed to detect more than four or five on the whole valve.
In such cases, and when, as often happens, the central area is
obsolete, it is a critical matter indeed to distinguish the valve
from C. radiatus, and in passing I may note that the " C. radiatus"
of my Holler's Typen-Platte is just one of these valves of
C. perforatus var. ceilulosa, with all its bright points complete.
C. obscurus may be mentioned as another species in which the
bright points, usually present, may be either totally absent or
reduced to a very small number. On the other hand the points
often occur in species which are normally without them. I have
met with instances of this kind in C. aster omphalus, on a narrow
unilateral area where the cellules are separate and rounded. In
a slide from Cambridge, Barbados, there are numerous valves of
C. excavatus, most of which display these minute cellules, and in
some valves not only at the origin of the radial series, but
profusely interspersed among the large areolae all over the
surface, even in places other than the angles of the areolae. And
I have a curious valve of Endyctia oceanica, in which these
minute cellules form the principal part of the areolation, the
ordinary large cells only existing in scattered groups of four or
five, surrounded on all sides by the network of small ones.
I have referred already to the small importance to be attached
•to mere differences in the size of the areolation, but I would
further remark that it must by no means be assumed that only
small differences are to be disregarded. Valves of C. concinnus
may have only four cellules in 0*01 mm., while others may have
as many as twelve, though the valve may be much larger. And
I have seen a frustule of C. excentricus in which one valve was
twice as finely marked as the other. Such instances show forcibly
the futility of distinctions founded on the size of the areolation.
24 W. M. BALE ON SOME OF THE DISCOID DIATOMS.
\
The structure of the valve-border is a feature which has not
always received sufficient attention from observers, who have
overlooked peculiarities which might be of service in classification.
This refers to the general character of the border, and more
particularly to the minute appendages which it frequently bears.
The apiculi which form a circlet at the margin of many species
are familiar to all observers, more especially those which in some
of the Fasciculati and Cestodiscoidales attain a prominence which
could not fail to attract attention. But those which are
asymmetrical, and of which only one or two appear on each valve,
have hitherto singularly escaped notice, except in a very few
instances, where they are more conspicuous than usual. For
example, in the robust form of C. lineatus, described as C. leptopus,
a single larger apiculus, farther in than the rest, is quoted by
Rattray as distinguishing C. leptopus from its allies. Y~et in
fact it is not peculiar to this form, a similar apiculus, but more
delicate, being easily discoverable in other and more nearly
typical forms of C. lineatus. Further, it is equally a feature of
C. excentricus, and I find it commonly present, though apparently
hitherto unnoticed, in forms of that species from such different
localities as Port Phillip, Cuxhaven, Santa Monica, and Peru and
Bolivia guanos. (There is, of course, no justification for the line
of demarcation drawn by Battray between the respective groups
of the Lineati and the Excentrici. The two type species are con-
nected by intermediate forms, and the same remark applies to
C. excentricus and C. subtilis.)
Among the Badiati the tendency is towards the production of
two apiculi, which occupy positions about one-third or one-fourth
of the circumference apart. They are found in many species,,
though strangely enough I can find no mention of them by any
observer except in the cases of G. concinnus and C. centralis, in
both of which forms they are very conspicuous. Battray says
that C. centralis is distinguished from C. asteromphalus by these
apiculi, and cannot be united with it in the same species, as pro-
posed by Grunow. An unfortunate dictum, since all, or nearly
all, of the numerous varieties of C. asteromphalus agree precisely
with C. centralis in this respect, while such apiculi, but more
rudimentary and indefinite, are found in a wide range of forms
comprised under C. marginatus, C. perforates, C. apiculatusr
C. borealis and others. Their minute size and indefinite form
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 25-
cause them to be easily overlooked against the coarsely marked
background of the valve-areolation, but in C. concinnus and
G. centralis they are more conspicuous, owing largely to the more
delicate and transparent condition of the valve.
The key to the position of these apiculi is, however, to be found
in certain modifications of the valve-border which occur in the
vicinity, and which indeed are often obvious when it is difficult
or impossible to detect the apiculi themselves. These modifications
may take the form of a thinning away of the valve-surface (C.
marginatus), or an apparent notching of the margin (C. borealis,
C. diorama, etc.), or a sinuation of the inner edge of the thickened
border (G. aster omphalus) . In the last species this marginal
structure is very conspicuous, at least in the robust valves, and it
is shown in Schmidt's figures of C. biangulatus and one or two
others.
In C. perforatus and C. apiculatus (at least in the areolate
forms) two minute notches in the extreme margin of the areo-
lation can in most cases be seen, and by careful examination the
apiculi may generally be found opposite them, but they appear
no more than a slight thickening of the silex, wThich would
certainly never be noticed except for the marginal clue. In
C. marginatus the coarse radial structure of the marginal zone is
thinned away over two comparatively large areas, sometimes very
noticeably, but the apiculi themselves are difficult to make out.
The apiculi are most fully developed in C. centralis and C.
aster omiAalus. They are best seen by examining the inside of
a large valve in which the marginal part is steeply convex, so
that the apiculi, which project into the valve a little above the
rim, can be observed without the interference of an immediate
background. The apiculus takes the form of a minute disc,
attached by a central point, and bearing a sub-globular or irregular
mass. The border in C. asteromphalus is usually widened in-
wardly so as to form an annular projection into the cavity of
the frustule. The extent to which this widening takes place
varies greatly, even in the same variety ; but whatever its width,
so long as it projects inwards at all, it is sinuated under the
apiculi, which are always uncovered, so that the sinuations are
deeper as the valve-border is wider. The structure would seem
to imply the presence in the living organism of some direct
communicating filaments between the apiculi of the two valves,
) W. M. BALE ON SOME OF THE DISCOID DIATOMS.
on which the inward extension of the border must never encroach.
I have had no opportunity of proving whether this is so, or even
o: ascertaining whether the apiculi of the two valves are opposite,
except in a single instance — a large cylindrical frustule of C.
mirificus mounted in zonal view, and in this the apiculi are
opposite.
In C. gigas the apiculi are, if present, obscure, and I can find
no marginal indications of them. C. diorama and allied forms,
however, often classed as varieties of C. gigas, have the border
distinctly marked with two apparent notches as in C. perforatus.
C concinnus has distinct apiculi, and many specimens have in
addition crescentic processes outside the valve, partly surrounding
the point at which the apiculi originate. These valves are known
as Eupodiscus Jonesianus Greville (E. commutatus Grunow), but
I do not think they have any claim to rank even as a variety.
They are abundant in slides from Ouxhaven, mixed indis-
criminately with valves having the internal apiculi only.
While several forms besides those which I can identify with
the foregoing species share in the peculiarity in question, there
are many others in which I have failed to detect it. Such are the
thick variety of C. Oculus Iridis found in the Mors deposit, also
■C. radiatus. In more typical forms of C . Oculus Iridis, however,
careful search has disclosed two apiculi, which are simple bacillar
projections into the cavity of the frustule.
Apart from these appendages the structure of the border itself
has in many cases not received sufficient attention as a help in
classification. Some species have distinct borders with markings
quite different from those of the valve generally, others have the
areolar structure continued to the extreme margin without
interruption ; in some the edge is turned over, in others it is
quite flat, and frequently the specific diagnosis contains no
hint of the character of the valve in this respect ; so that of two
valves, differing widely in this particular, it may be impossible to
decide which of them corresponds with the specific description.
C. concinnus and C. centralis may serve to illustrate this. Both
are very convex, but in the former the marginal part is slightly
flattened, the areolae diminish to a very minute size, and are
succeeded by an extremely narrow hyaline border, thinning
away so as to show only a smooth single contour. In a typical
C. centralis, on the other hand, the valve curves downward to the
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 27
extreme edge, and the areolae are of an appreciable size throughout,
while the border is not thinned away, so that on focusing the
margin there is visible a distinct double contour, with the walls of
the last row of cellules showing as coarse transverse striae.
Several species exhibit a tendency for the border to become
wider in proportion as the valves are smaller. C. obscurus and
V. apiculatus are instances of this. In both these species I have
traced a series down to forms with wide borders, which are
only to be distinguished with difficulty from C. marginatus.
In Nottingham and other American deposits such forms of
C apiculatus are common, and one of them figured by Schmidt
(PI. 62, f. 11, 12) has been referred by Rattray to C. marginatus.
In several species of the Radiati the angles of the areolae often
tend to become thickened, so that in a certain focus there appears
to be a bead at each angle. This feature has no specific im-
portance, and I agree with Rattray that the presence at each
a,ngle of a distinct spine, as occasionally found, is of no greater
consequence.
I have already referred to the close affinity which exists
between the Excentrici and the Fasciculati, e.g. between C. ex-
centricus and C. subtilis. Grunow mentioned this affinity, but
Rattray says that it is remote. Grunow's view is undoubtedly
correct. In a typical G. excentricus there is a central cellule,
and surrounding it a circle, generally of seven. Each of these
seven is the centre of an arcuate line of cellules, extending to
the margin on either side, behind which is a succession of similar
arcuate series, so that the whole of the cellules may be regarded
as forming seven fascicles, crossing each other symmetrically, so
that no division-lines exist, and for the most part each cellule
will form part of three different fascicles. In C. subtilis and
C. symbolophorus the number of fascicles is greater, and the
divisions between them more abrupt, especially in the central
part of the valve, so that the fasciculation is more manifest, but
even in these forms the fascicles blend towards the margin in the
same way as those of C. excentricus. I have seen a frustule of
the latter species in which one valve was normal, while the
other was far more finely marked, and was as distinctly
fasciculate as C. subtilis.
I should mention that the C. subtilis referred to is Grunow'
typical form, which is quite different from Rattray's, though
W. M. BALE ON SOME OF THE DISCOID DIATOMS.
that observer quotes Grunovv as his authority. He describes
C. subtilis as apiculate, and differentiates other species from it
by the absence of apiculi. Yet Grunow says expressly that
C. subtilis is non-apiculate. " Der Ausgangspunkt fiir alle diese
Formen ist der stachellose C. subtilis (Ehr. partim), Gregory,
Grunow " (Diat., F.-Josef Land, p. 81). This form, which is similar
to C. symbolophorus, but without the stellate markings at the
centre, also agrees well with Rattray's own account of Ehren-
berg's original species. It is not common, and Yan Heurck
figures it from guano, not finding it in European gatherings.
But Peragallo, like Rattray, though claiming to follow Grunow's
authority for the type, has figured and described a totally different
form — an apiculate variety.
Actinocyclus. — The excessive multiplication of specific names
which encumbers the Coscinodisci has not been carried out to a
corresponding extent in the much smaller group of the Actino-
cycli (ignoring, of course, Ehrenberg's multitudinous pseudo-
species) ; still there is no doubt that an undue regard for certain
points of structure has led to the establishment of several species
on insufficient grounds. Rattray's monograph admits about
seventy species : Fome of these have no claim to recognition, but,
on the other hand, I find that about fifteen out of thirty-four
species or varieties which I possess cannot be identified with any
of Rattray's descriptions. He has adopted in this monograph
the plan of furnishing extremely long and minutely detailed
descriptions, a method which renders identification more certain
when one is dealing with the precise form described, but does
not allow for the variations which constantly present themselves
even in a single gathering. In fact, as I have remarked in
reference to Coscinocliscus, many of these are not descriptions
of species, but of individual diatoms. Mr. Rattray uses five
places of decimals to express the fraction of a millimetre which
corresponds to the diameter of a pseudo-nodule ! Of what
possible use can such measurements be when applied to structures
so notoriously variable ?
Before discussing the range of variation in the genus, and
as I shall refer repeatedly to the commonest species — A. Ehren-
bergii — I must premise that I use that name in the sense in
which it is used by Ralfs himself, and by Yan Heurck, Grunow,
Peragallo, and, so far as I know, by all other observers except
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 29
Rattray, who has unaccountably assigned the name to an entirely
different form, while describing the true A. Ehrenbergii as
A. moniliformis Ralfs. A. Ehrenbergii was described by Ralfs
from his own knowledge, while A. moniliformis was merely a
name given by him to certain forms from Oran and Virginia,
which he had not seen, but which he judged from Ehrenberg's
tigures to be distinct, the distinction consisting in the division
of A. Ehrenbergii into compartments by double lines, while
A. moniliformis was divided by single ones. There is really no
difference, except such as depends on the size of the valves and
the number of the fasciculi. In small valves, containing few
fascicles, the interfasciculate rays form a wide angle with the
other series, and are therefore very marked ; and these are the
" single series of dots " referred to by Ralfs. In large valves
the fascicles are numerous and narrow, so the interfasciculate
rays form a small angle with the other series, which, stopping
short at various points, leave a double row of subulate blank
spaces along the sides of each primary or interfasciculate ray,
and 'these subulate areas constitute the "double lines" of Ralfs.
That the small valves from Oran and Virginia, and the large
ones from Cuxhaven, etc., are one and the same species is fully
recognised, however, by Rattray, but he names them A. monili-
formis. To any one who reads carefully Ralfs' account of
A. Ehrenbergii there can be no possible doubt as to the identity
of the species. It was established specially to include the
many-rayed forms described by Ehrenberg, which mostly occur
at Cuxhaven ; Ralfs also states that it is " very fine in Ichaboe
guano," and that most of the forms can be obtained therein ;
and further, that it is " common, both recent and fossil." One
species, and only one, answers perfectly to this description,
namely, that which Rattray calls A. moniliformis, but which,
in its larger forms, at least, has been recognised by observers
generally as A. Ehrenbergii. Rattray might have been justified
in preferring the name of A. moniliformis on the ground of
priority, but he has failed to perceive that the forms which he
has placed under it are no other than the A. Ehrenbergii of
authors, and has inexplicably assigned the name A. Ehrenbergii
to a species (or variety) differing entirely from that described
by Ralfs. It is not found at Cuxhaven, nor, so far as is known,
in Europe at all ; it is far from being common, either recent
30 W. M. BALE ON SOME OF THE DISCOID DIATOMS.
or fossil, and it is not found in Ichaboe guano. It is dis-
tinguished from the true A. Ehrenbergii by its concentrically
undulated valves, by its strong iridescence, and by its sharply
defined zones of colour under low powers. Its granules are
also more closely and regularly arranged, forming over the
greater part of the valve a very regular areolation. To
distinguish it from the true A. Ehrenbergii I propose for it
the specific name of A. rex. I have only found it in the
deposits of Nottingham, Curfield, Atlantic City, and Lyons
Creek. Rattray's localities are necessarily unreliable, so far
as they are given on the authority of other observers, of whom
some at least (Ralfs, for example) were referring to the true
A. Ehrenbergii, and not this form at all.
Rattray's description of this species, however, requires amend-
ment, especially as regards the contour of the valve. He says-
that large valves have the centre depressed, and two concentric
elevated zones between the centre and the border, while small
valves have the centre depressed, and are convex between it and
the border. This is correct so far as some of the valves are
concerned, but in others the surface elevations and depressions
are in the opposite order. Thus in large valves the centre is
convex, and there is one elevated zone between it and the border^
Evidently the frustule is concentrically undulated as a whole,
the depressions of one valve corresponding to the elevations of
the other. So in the case of the small valves with depressed
centre, others, evidently their counterparts, have the centre
convex. Some of the valves in my slides are 0*20 mm. in diameter,
Rattray's maximum being 0*17.
The largest European species is, according to Rattray, A.Ralfsiir
of which I have not seen specimens agreeing entirely with
Peragallo's description of the type ; but among the forms of
A. Ehrenbergii abundant in slides from Cuxhaven and Ichaboe
guano are many which agree with that description in the
arrangement of the fasciculi and subulate areas, though not in
the brilliant appearance, the very large pseudo-nodule, nor the
concentric arrangement of the granules. One has only to read
the descriptions of Ralfs, Yan Heurck, Rattray and Peragallo
to see that no two of these observers agree as to the respective
characters of A. Ralfsii and A. Ehrenbergii, which is nob sur-
prising if, as Peragallo states, every intermediate gradation
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 31
exists between the two types. This agrees with the views
expressed by Grunow, Lagerstedt, and others ; it would seem,
therefore, that Peragallo is justified in treating A. Ehrenbergii
as at most a variety of A. Ralfsii.
Most species of A.ctinocyclus have the markings arranged on
the same general plan as A. Ehrenbergii. The surface of the
valve is divided into cuneate areas by a number of moniliform
series of granules (the interfasciculate rays), which radiate from
the centre, or near it, to the marginal zone. Each cuneate area
contains a fascicle of similar moniliform series, but only the
central one is strictly radial, and all the others are parallel
with it ; and as they all stop short of the interfasciculate rays
they are necessarily shorter as they approach these rays. The
great difference in the aspect of the valves dependent on the
small or large number of fascicles has already been mentioned.
In the largest valves, where they are most numerous, they are
so narrow that they consist of very few series of granules, and
the angles which they form with the interfasciculate rays are so-
small that at first sight it might appear that all the series are
« truly radial. Such is the structure in the largest valves of
A. Ralfsii, A. Ehrenbergii, A. Barklyi, etc., but the markings are
just as truly fasciculate as in the smallest form's, though the
fasciculi are not so patent. No amount of variation of the
kind described, therefore, is in itself of importance in classification.
But great irregularities in the arrangement of the markings
prevail, and there is' perhaps no other genus in which valves
of one and the same species present such different aspects.
While one valve may have the interfasciculate rays very distinct,
all starting from a circular central ring of granules, and all the
series well defined, the next may present at first sight a very
different aspect, owing to the denseness of the granulation, and
in yet another much of the appearance of regularity may be
lost owing to its sparseness. This is especially noticeable in the
centre of the valve, where there may be a regular area, with
perhaps a few granules in the centre, while in other cases there
may be no definite area at all. Usually the interfasciculate rays
stop short at a little distance from the centre, but in the small
valves of A. Ehrenbergii from Oran, as Mr. Rattray points out,
they cross each other. Another point of variation is the width
of the blank areas along the sides of the interfasciculate rays.
32 W. M. BALE ON SOME OF THE DISCOID DIATOMS.
Jl, fasciculatus Castracane is distinguished by the notable width
■of these areas, but the character is of no specific importance.
A, Ehrenbergii often exhibits such areas, and I have seen them
in one valve while the other in the same frustule showed
scarcely a trace of them. They may even exist on only a part
■of a valve. So far as Castracane's figures show, there is nothing
to distinguish his species from A. Ehrenbergii.
A frequent phenomenon in the genus is the occurrence of
regular or irregular blank areas crossing the rows of puncta,
•often in a sub-concentric fashion, and A. crassus is a form in
which the apparent irregularity of the markings from this cause
has been made a ground for specific distinction. Yet both Van
Heurck and Peragallo, who admit the species, show by their
figures that the markings are as in A . Ehrenbergii, except in so
far as the granules ard obliterated over certain irregularly sub-
concentric areas. I find nothing here to warrant the separation
•of the form as a distinct species.
The interfasciculate rays are also liable to interruptions, and
Castracane has described a species — A. complanatus — in which
they are said to be wanting, though the valve is of the ordinary
fasciculate type. I greatly doubt the correctness of this, not
merely on a priori grounds, but owing to Rattray's identification
of this species with the form distributed by Moller as A. Ralfsii.
Now the " A. Ralfsii1' of my Typen-Platte is simply one of the
forms of A. Ehrenbergii in which the fasciculation is similar to
that of A. Ralfsii, and which abound in Cuxhaven and Ichaboe
guano material. The interfasciculate rays are certainly not
wanting, though doubtless obscure and irregular in parts. Many
otherwise similar valves occur in which there is no noticeable
irregularity of these rays.
The general aspect of the valve depends largely on the position
and distance of the granules relatively to the others in the same
und adjacent rows of the fascicle. In A. Barklyi the granules of
each row are very close to each other, but not so close to those
of the next rows ; the rows therefore remain distinct from each
other even to the border. In A. Ralfsii type and var. sparsus
the granules of adjacent rows are mostly side by side, so that
they form straight lines crossing the fascicles, thus having as a
whole a sub-concentric disposition ; they are also distinctly
separated from each other. In A. Ehrenbergii there is much
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 33
variation, the granules often forming irregular zigzag lines
crossing the fascicles; generally, however, the tendency is for
the granules of adjacent series to alternate with each other, and
also to be somewhat crowded, so as to form a quincuncial
arrangement, which in any case prevails towards the border.
In A. rex the alternate arrangement is much more pronounced,
and as the granules are crowded equally all round the markings
form a very regular areolation over the greater part of the
valve.
The appearance of the granules themselves varies remarkably
in the same species. In A. Ehrenbergii some valves show them
in the best focus as minute, dark, sharply defined circles, while in
others they are more pearly, and show, much more readily, a
central black spot. When crowded, especially towards the
border, they form a distinct areolation. In A. rex the latter
type predominates, but near the centre the granules are more
pearly. In A. Barklyi and A. ellipticus they vary much as
in A. Ehrenbergii. And in all these species they appear some-
times as dark, well-defined puncta. Peragallo has figured a form
which he calls A. nebulosus, and which is practically a hyaline
valve of A. Ehrenbergii with fine puncta instead of granules, also
a corresponding form with the puncta arranged like the granules
of a typical A. Ralfsii. He thinks these valves are probably the
result of cleavage, of the correctness of which opinion I think
there can be no doubt. Corresponding forms of A. Barklyi are
found in hundreds in slides of that species, often so delicate and
colourless that they become invisible on a slight alteration of the
focus. How many layers has a valve of A. Barklyi% When
manipulating one under the microscope I saw it divide into
three, one extremely thin and hyaline, and another somewhat
thicker, but still less robust than the main disc. Here the
question of colour comes in for consideration, for it is probable
that the colour as well as the appearance of the granules depends
more or less on the " state " of the valve — whether it consists of
more than one plate for instance, or whether the two plates
include a film of air between them. A. rex is the most brightly
coloured form I have seen, having the colours in sharply defined
zones. A. Ehrenbergii is usually blue, green, purple, or brown,
often showing more than one colour, but not in sharp zones. A .
Barklyi varies much in the same way, but is exceptionally liable
Journ. Q. M. 0., Series II.— No. 72. 3
34 W. M. BALE ON SOME OF THE DISCOID DIATOMS.
to exhibit a dark, semi-opaque aspect. But all these species
usually include forms of the same size, contour and arrangement
of markings, but of a soft brown colour, uniform throughout
or nearly so, and generally with fine punct'a. Are these complete
valves, or secondary plates, or primary plates from which the
secondary ones have been detached ? Some of these brown discs
have the silex of the subulate areas so thickened as to appear
black under a low power. Valves of A. Ehrenbergii with
sharply defined granules and clear, distinct subulate areas mostly
appear blue under low powers, with the subulate spaces white.
Others, such as that described above, from Holler's Typen-Platte,
are more commonly green or purple, and show no white streaks,
though having large subulate areas, the substance of the valve
itself appearing to have a dusky tint. The bright colours of
these species can only be seen when dry or mounted in balsam
or a similar medium, while in water they are colourless.
No other diatom known to me presents such endless variety
of marking as A. Barklyi, and occurring, as it does, in such
profusion, it is especially suitable for a study in variation. This
diatom is of interest as being probably the first to be named in
Australia, it having been described by Dr. Coates in the Trans-
actions of the Royal Society of A^ictoria for 1 860, under its
present name. Rattray incomprehensibly calls it " Actinocyclus
Barklyi (Ehr.) Grun.," though he knew that it was named by
Coates, and not by either of the authors cited. He quotes a
reference to it in the Q. J. M. S. for 1861 (wrongly quoted as
"Plate CXXXVIII." instead of "Page 138 "), but does not refer
to Coates' original description. It is distributed by Moller under
the name A. dubius Grunow. It is one of the largest of the
genus (perhaps the largest), specimens in my slides attaining a
diameter of 0*24 mm., or more than double the maximum size
assigned to it by Rattray.
In normal valves the fasciculi are arranged much as in A.
Ralfsii, but great variety exists in the denseness or otherwise of
the granules, which, as in A. Ehrenbergii, also vary greatly in
sharpness. But it is in individual departures from the normal
arrangement that the tendency to variation exhibits itself in
such an extraordinary degree. In many cases the markings are
interrupted at a uniform distance from the centre, so as to form
a ring, and several such concentric rings may exist on one valve,
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 35
dividing it into zones. Sometimes the markings are denser on
one of these zones than elsewhere. Very often the zones form
hyaline bands on which the granules are wanting, and the
structure may be further complicated by the addition of radial
hyaline bands, e.g. two hyaline zones may be joined by a number
of equidistant radial hyaline areas so that the space between
them is divided into a circular series of sub-rectangular com-
partments ; or a broad circular zone may be filled with hyaline
patches of all sorts of irregular shapes. The radial series of
granules may be all curved in a spiral fashion (a variation
which also occurs in C. Ehrenbergii), and I have specimens in
which the central portion, as far as the first circular interruption,
has the moniliform series all contorted in the most extraordinary
manner. As in A. rex, etc., the subulate areas may be either
darker or lighter than the rest of the valve. There may be a
small central area, or the whole centre of the valve may be
sparsely and irregularly marked.
I find that in some slides concave and convex valves are mixed
about equally, leading to the conclusion that the two forms
represent opposite valves, as in A. rex, but in other gatherings
I find many concave valves to every convex one. Rattray de-
scribes the valves as flat in the centre and otherwise convex, but in
numerous cases the convexity (or concavity) is uniform throughout.
Asteromphahis. — In this genus the lines which radiate from
about the head of the centro-lateral area to the apices of the
areolate compartments have been assigned too much value in
classification. Whether they originate from a single point, or
whether they bifurcate, is absolutely immaterial, and the presence
of geniculate bends in their course is, in some species at least,
equally unimportant. A. Hookeri, which is not rare in one of the
"Challenger" Antarctic soundings, illustrates this. The forms
with six, seven, eight and nine rays, which represent four of
Ehrenberg's "species," also a ten-rayed form, occur in slides
which I have prepared from this material, and 1 find the
geniculations of the radial lines very marked in some valves,
while others show no trace of them ; others again exhibit a mixed
condition. A good deal seems to depend on the size of the valve,
the geniculate lines being most common in the smaller ones.
Certain species are subject to variation in the outline.
A. Cleveanus, as figured by Schmidt, has a rather narrow ovate
36 W. M. BALE ON SOME OF THE DISCOID DIATOMS.
form, but in mud from Manila it has a broader outline, and
I found one valve perfectly circular.
Actinoptychus. — This genus is distinguished by its valves being
divided into six or more radial cuneate compartments, which are
alternately raised and depressed, the markings also differing (in
normal valves) on the elevated and depressed areas. On what
we may call, for want of a better term, the primary areas
{Hauptfelder of Schmidt), the coarse markings are usually more
robust, and often of different form, from those on the secondary
areas (Nebenf elder of Schmidt) ; further, the primary areas
usually bear a tooth or process near the margin, with, in some
species, a radial line connecting it with the umbilicus ; while the
secondary areas sometimes terminate in a submarginal hyaline
band, which is not found in the primaries. The fine striation
also is commonly different on the two sets of compartments.
The striation is generally fairly uniform within the limits of
a species, but the secondary markings, consisting of hexagonal
or irregular reticulation, or systems of branching veins, is most
variable in its distinctness, and is often wanting. When this
occurs it is generally assumed to be the result of the detachment
of the separate layer of the valve which is thus marked, but in
view of the fact that different valves exhibit every possible
degree of obsolescence of these markings, I have no doubt that
in many cases they have not been developed.
Among the characteristics to which too much importance has
been attached in classification are — the number of areas, the
substitution of primary for secondary areas (so that all the areas
are alike), the presence or absence of the secondary markings,
also of the lines connecting the umbilicus with the processes, and
the presence of small variations in the striation. The adoption
of these purely artificial distinctions has led not only to the
undue multiplication of specific names, but, what is worse, to the
lumping together of forms which are by no means closely related.
In several species there are six areas, a number which is
rarely, if ever, departed from. Such are the forms composing
the group of which A. boliviensis is typical. In the majority of
species there is no constant number; for example the beautiful
A. Heliopelta, valves of which usually have six, eight, ten, or
twelve areas (constituting Ehrenberg's four species of Heliopelta),
while more rarely there are fourteen or sixteen. A. undulatus,
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 37
the most widely distributed species, is found in most localities with
six areas only, yet in some Calif ornian deposits it occurs freely
with up to eighteen areas, possibly more.
A. undulatus is a species which well illustrates the tendency of
the genus to vary in several directions, but the variations are
so numerous and so closely linked, and their relationships so
obvious, that they have not been made the basis of so many
pseudo-species as might have been expected. I have noted about
twenty-five forms sufficiently distinct to admit of their being
separated for convenience of cataloguing, but few of them are so
characteristic as to constitute definite varieties. In forms of
average size, which may be considered fairly typical, the secondary
markings are commonly about four in O'Ol mm., while in the
var. microsticta of Grunow, there may be about seven, and in
large forms like forma maxima Schmidt, there are only one and
a half to two. The reticulation may be either hexagonal or
irregular, robust or faint, and sometimes entirely wanting. The
sub-marginal processes are said to be sometimes absent ; in fact,
both W. Smith and Yan Heurck appear to regard this condition as
typical, but I have not seen specimens without some trace of them.
(The obsolete genus Omphalopelta comprised the valves with
processes.) The processes may be very small, appearing merely
as a slight thickening of the border, or may be placed a little
farther in, presenting a somewhat irregular keyhole-shaped
aspect. In many forms the secondary areas have on their
margin a small hyaline patch in the corresponding position to
that occupied by the processes in the primaries. On both sets
of areas the outermost portion, immediately adjoining the margin
proper, usually bears radial lines, being continuations of the
boundaries of the last row of secondary markings, which, like the
secondary markings generally, are most robust on the primary
areas. The rim may be smooth, or may have few or many
minute apiculi scattered over it. The puncta which compose the
striae of the primary areas are arranged in quincunx, so that the
striation is the same as in Pleurosigma angulatum, but those of
the secondary areas form two sets of diagonal striae cutting each
other at right angles, as in P. formosum. Schmidt describes as
A. biformis valves in which these two sets of striae meet at
rather less than a right angle, so that a third set is visible,
closer than the other two, and crossing the area transversely.
38 W. M. BALE ON SOME OF THE DISCOID DIATOMS.
Some valves which I have seen with this character were in all
other respects similar to normal valves of A. undulatus, among
which they occurred, and I see nothing to justify their separation,
the slight divergence from the rectangular arrangement of the
striae being no more than is often found in P. formosum. Some-
times the striae meet at more than a right angle, so that the
third set is radial instead of tangential. If Schmidt's species
were accepted, this should make another species ! The striae are
sometimes nearly or quite obliterated on small patches at the
outer angles of the secondary areas, and occasionally along the
margins ; in some forms again they are wanting or represented
only by a few scattered puncta on a great part of those areas.
The umbilicus varies greatly in size, and may be either hexagonal
or may have three concave sides. Much variation exists in the
extent to which the areas are inflated, or, in other- words, in the
depth of the undulations.
A consideration of the variations of this diatom will show how
many features there are which, met with in isolated forms, may
lead to the undue multiplication of species.
In several species, perhaps in the genus generally, there is
a tendency to produce valves in which the secondary areas or
" Nebenfelder " are replaced by primary ones or " Hauptfelder,"
so that all the areas become alike, except in their elevated or
depressed condition. Van Heurck has figured such a form of
A. undulatus — the forma sexapjiendicidata, which he says may
co-exist in the same frustule with the normal form. He refers
only to the presence of a process on every area, and does not
mention that the areas are otherwise modified, which, however,
I have always found to be the case. Other varieties of
A. undulatus exhibit the same tendency ; thus the large forma
maxima found in the Nottingham deposit is accompanied by its
"forma sexappendiculata" as also is an equally large variety
which only differs from it in the strongly apiculate margin. In
all these cases the compartments all correspond exactly with the
normal primary areas, both in the striation and the coarser
secondary markings. There may possibly be varieties with this
as the usual condition, as I have found one or two such forms
sparsely distributed in material where I noticed no typical valves
to which they might correspond.
In A. Heliopelta also valves are formed in which all the areas
are alike, instead of alternately primary and secondary.
It is to be noted that in all species where this phenomenon
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 39
occurs it is always the primary area, with its process, which is
duplicated ; we never see valves with all the areas alike and
having the distinctive markings of the secondary ones.
Notwithstanding that it has been recognised that in A. undu-
latus the variation in question has no specific importance, being
found, in fact, in frustules otherwise normal, a parallel variation
in other cases has been made a ground for the foundation of new
species, even by observers as recent as Grunow and Schmidt.
Such instances are A. Janischii Grun., which, as I shall
demonstrate, is only a state of A. splendens, and A. Molleri
Grun., which is a form of A. adriaticus Grun. Van Heurck says
of A. Janischii that it " se distingue de toutes les autres especes
du genre en ce que la valve a toute juste moitie autant
d'ondulations que de divisions, de facon qu'une elevation n'est
suivie d'une autre elevation que pres da deuxieme appendice
suivant. Une espece analogue mais plus petite est V A. Jfolleri
d'Adelaide, qui se distingue en outre par sa structure plus
delicate et l'absence d'une ligne mediane." This is simply
equivalent to saying that each area, instead of each alternate
area, bears a process, and it is surprising that the writer did not
observe that the character referred to as so exceptional was no
other than he has figured in the same plate in the forma
sexappendicidata of A. undulatus.
A. glabratus Grunow and A. Janischii Grunow are, in part at
least, forms of A. splendens, but there is a difference in the
relationship which they bear to that species, A. glabratus
simply consisting of valves wanting the secondary markings,
while A. Janischii is an internal disc. A. splendens commonly
has a distinct secondary layer showing more or less branching
venation, with the typical distinction between primary and
secondary areas, but a gathering usually includes a propor-
tion of valves in which the secondary layer is wanting ; and
although there is every possible gradation, the smooth valves
have been described as a doubtful species, under the name of
A . glabratus. Also accompanying them are valves in which all
the compartments bear processes, and to these the name
A. Janischii has been given, Janisch having figured one of
them (as Halionyx vicenarius) in his paper on diatoms from
guano. Tn Peru guano A. splendens is one of the commonest
species, and the typical valves, with their glabratus-iovms and
Janischii-iovms, are readily obtained. In a Cuxhaven gathering
I also find all three forms together. And in a slide of Thum's,
40 W. M. BALE ON SOME OF THE DISCOID DIATOMS.
which contains a very robust variety, all three forms are
similarly associated. In the valves described as A. Janischii
the marginal sculpture differs somewhat from that proper to
A. splendens, but this is a necessary concomitant of the substi-
tution of primary for secondary areas. In A. splendens, as in
several other species, the secondary areas terminate in a sub-
marginal hyaline band, which encroaches slightly on the primary
areas at each side of it. When, however, all the areas have the
same structure, this band is wanting, all except the small portion
which properly belongs to the primary areas, so that a small
rounded hyaline patch opposite the edges of the compartments is
all that remains.
The relationship between these forms has always appeared to
me obvious, as it evidently did to Ralfs, who describes A. splendens
as having a tooth on each compartment, or sometimes only on
alternate compartments. In order to obtain actual proof of this,
however, it occurred to me to examine some Peru guano
cleanings which had furnished numerous slides, but in which the
complete frustules of A, splendens, where they occurred, had been
left. I picked out ten of these and mounted them in balsam,
with the result that I found that three out of the ten contained
valves of the so-called A. Janischii, each being included in a
frustule between two of the normal valves. In all cases where I
have examined whole frustules of A. splendens I have found that
the two valves were either alike in the number of areas, or one
valve had a pair more than the other. Thus, if one valve had
sixteen areas it could be predicated that the other would have
fourteen, sixteen or eighteen. Where an internal disc was
found (A . Janischii) it had the same number of areas as one of
the outer valves. In the slide referred to one frustule had the
outer valves with fourteen and sixteen areas respectively, and the
internal disc with sixteen ; another had the outer valves with
sixteen and eighteen, and the inner with eighteen ; and the third
had twenty throughout. The areas of the inner disc have the
processes rather smaller than those of the outer valves, and
nearer the margin. Though the inner disc is usually smooth,
like the so-called A. glabratus, this is not invariably the case. I
have a specimen covered with reticulations as distinct as in the
typical valves.
In Van Heurck's opinion several genera, as well as species,
have been founded on mere internal valves of various species of
Actinoptychus (as also of Asterolampra). Such are Debya and
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 41
Gyroptychus, Debya being an internal disc of A. undidatus, very
unlike the outer valves, and found by Van Heurck inside the
normal frustules. The A. jjellucidus Grunow, figured in Van
Heurck's synopsis, PI. 123, fig. 1, is, as will be obvious to any one
who compares it with the figure of A. Heliopelta in the same
plate, merely a valve of the latter with the border wanting and
the secondary reticulation undeveloped. In a genus-slide by
Thum I have several such valves, but for the most part they
retain a little more of the border, showing the origin of the
spines, and some of them also have the secondary markings more
or less distinctly indicated.
In many marine gatherings from Port Phillip a form of
A. adriaticus is found in great profusion, of which a specimen is
figured in Schmidt's Atlas, PI. 153, fig. 14. It varies greatly in
the distinctness or otherwise of the secondary markings, and
especially in the presence or absence or fragmentary condition of
the narrow radial lines which in the typical A. adriaticus, as in
A . splendens, run outward from the umbilicus, or near it, to the
processes. In most slides a few specimens may be found with all
the areas alike, and a process on each, and it is this form which
has received the name of A. Molleri Grunow.
Normally the areas are arched at the ends, as shown in Van
Heurck's figures, the secondary ones being shorter than the
primary, with a wide hyaline band outside them, but as in the
form called A. Molleri they are all primary areas, and conse-
quently of the same length, the hyaline band is reduced to a small
triangular area at the junction of every two compartments with
the margin. All the variations of marking which occur in the
normal valves are found equally in this form, and their specific
identity is obvious. In reality, this so-called A. Molleri is the
true A. adriaticus described by Grunow, his original figure
showing a valve with processes on all the areas, and exactly the
same marginal sculpture as described above. It is true A. Molleri
is supposed to be without the radial lines to the processes, but
Grunow recognised in his original description of A. adriaticus
that these lines might be present or not, in which he was
certainly correct.
These radial lines, however (sometimes called pseudo-raphes),
appear to be considered by Van Heurck as distinguishing
A. adriaticus from A. vulgaris, though he admits a possible
exception in A. adriaticus var. pumila. In the common
Australian form, however, it is obvious that the presence of
42 W. M. BALE ON SOME OF THE DISCOID DIATOMS.
these lines has no specific or varietal significance whatever.
Almost every gathering shows valves both with and without
them, and innumerable specimens exhibit an intermediate con-
dition, i.e. where the lines are more or less broken, or where they
are present on some of the primary areas of a valve and not on
others. They are scarcely ever complete, but generally stop
short of the umbilicus, as in the var. balearica. Valves without
them are otherwise identical with those possessing them, having
exactly the same range of variation in other respects, and this
applies equally to the so-called A. JIdlleri.
While reliance on such characters as the foregoing leads to the
improper separation of allied forms on the one hand, it tends in
other cases to the opposite error. Thus several varieties of
A. glabratus have been described, and while some are, as before-
mentioned, only smooth valves of A. splendeiis, there are others
which, so far as I know, cannot be identified with any special
form of that species, and which may probably be themselves
entitled to specific rank. A. vulgaris also, as generally under-
stood, includes forms which have really no close relationship.
One such form is nothing but A. undulatus^ as it is found in
Redondo Beach and other deposits, with mostly fourteen areas.
The deposit mentioned contains numerous valves of the ordinary
form, with six areas, a few with eight, ten and twelve, a good
many with fourteen and a few with sixteen and eighteen. The
structure of these is absolutely identical with that of the six-
rayed forms, and it is as absurd to separate them as it would be
to separate forms of A. Heliojjelta with six areas from those with
more. Other forms commonly ranked under A. vulgaris are
simply valves of A. adriaticus with the pseudo-raphes wanting,
as already described, while others seem to be similar, but with
deeper and more abrupt undulations. The undulations in
A. adriaticus are very shallow, so much so that Grunow origin-
ally described it as flat ; but in view of the considerable variation
in this respect found in the valves of A. undulatus and other
species, the character would seem to be of doubtful importance.
Probably the nearest approach to a really flat condition is
found in the three-sided A. mari/landicus, in which the six areas
show a very slight difference of level near the centre only, else-
where blending with each other imperceptibly. This species has
a more or less distinctly three-sided umbilicus, and appears to be
identical with the Symbolophora trinitatis of Ehrenberg. Ralfs
has argued against this view on the ground that >S'. trinitatis is
W. M. BALE ON SOME OF THE DISCOID DIATOMS. 43
circular, while A. marylandicus is three-sided, but in Atlantic
City slides valves of the latter species are found in which the
divergence from the perfectly circular form is scarcely perceptible,
so the objection falls to the ground.
It is sometimes stated as a character of the genus that the
depressions of one valve correspond to the elevations of the other,
so that the frustule is radially undulated as a whole. That this
is not alwavs the case is evident from the fact that the two valves
have often a different number of areas. But I find on comparing
a number of species that there is considerable variation in regard
to the undulations. First we have forms in which the undula-
tions extend to and include the rim itself, so that one valve
necessarily fits into the other. A striking example is A. trilingu-
latics, in which the whole valve is so strongly undulated that only
three points of the margin can be seen at any one focus. Then
we have such species as A. undulatus and A. Heliojwlta, in which
the undulations do not extend outward to the margin. Apart
from the border itself, the sub-marginal zone is about on a level
throughout, but the one set of areas is inflated as much above
that level as the other is below it. The border itself slopes down
rather steeply, but the depressed areas often reach as low a level
as the extreme margin. Still, the width of the hoop ensures that
such valves may be placed with the depressions opposite each
other without coming into contact. Lastly, in A. splendens the
depressions do not reach as low as the margin, while the eleva-
tions rise considerably above it ; even with a narrow hoop,
therefore, there is no question of the depressed areas of opposite
valves clashing.
According to the definitions of Ralfs and Yan Heurck, a
character of the genus is the division of the valve into equal
cuneate segments, which would exclude from it the A. hispidus
Grunow (Van Heurck, Synopsis, PI. 123, fig. 2), a species which
is described as having narrow elevated compartments alternating
with wide depressed ones. I believe, however, that the so-called
elevated compartments of A. hisjndus are not compartments at
all in the same sense as those of Actinoptychiis ; neither are they
elevations, but only appear so owing to having depressions on
each side of them. The valve is a shallow cone, by far the
greater part of which is occupied by about eight or nine broad
radial cuneate areas, all of which are depressions. The linear
rays or ridges are simply parts of the surface not included in the
depressions, but dividing them. These rays slope down evenly
44 W. M. BALE ON SOME OF THE DISCOID DIATOMS.
from the umbilicus and join the sub-marginal zone without any
interruption of the structure, which indeed is similar all over the
valve, except the narrow hyaline border. The valve is very thin,
covered with very delicate striae, crossing each other obliquely,
and most easily seen on the narrow rays. The secondary
markings consist of a fine, delicate, irregular reticulation, at the
angles of which are dark points or apiculi, which are larger and
darker on the narrow rays and sometimes round the inner border.
On each of the linear rays, near the border, is a minute process.
In Grunow's figure both the cuneate areas and the dividing rays
are abruptly truncate at the border, but my specimens do not
agree with this, as the narrow rays widen out in a regular curve
towards the border zone, with which they are continuous, the
cuneate areas having of course their outer corners rounded off
correspondingly, while they do not quite reach the border. Owing
to the thinness of the valve, however, and the depressions being
by no means abrupt at the outer ends, this character might often
pass unnoticed, unless the valve happens to be lying obliquely,
when it becomes more conspicuous. Possibly my specimens, which
were found in recent gatherings from Port Phillip, may differ
specifically from Grunow's guano specimens, but the late
Mr. Comber considered them the same.
I think the characters by which this species is distinguished
from all others of the genus are such as to entitle it to at least
the rank of a sub-genus, for which I would suggest the name
Radiodiscus. It is possible, however, that it may be brought
under the genus Actinodictyon Pantocsek, but I am uncertain
of the affinities of that genus, of which I have seen no specimens.
I have a single valve, apparently belonging to A. hispidus,
which differs in several respects from the usual form. Its
depressions are extremely slight, there are no secondary markings
and no apiculi, and the cuneate areas terminate in a hyaline
band, as in A. splendens, etc.; it also has exceedingly narrow
lines (pseudo-raphes) on the narrow areas ; the border is wanting.
It may be a varietal form, or possibly an internal disc, but its
pseudo-raphes and hyaline bands seem to indicate a closer affinity
with such forms as A. adriaticus than would be inferred from the
typical form.
Journ. Quckett Microscopical Club, Ser. 2, Vol. XII., No. 72, April 1913.
45
SOME NOTES ON BRITISH FRESHWATER RHAB-
DOCOELIDA— A GROUP OF TURBELLARIA.
By Henry Whitehead, B.Sc.
(Read January 28th, 1913.)
Plate 4.
The members of the group Rhabdocoelida are very similar as
regards appearance, shape and movements to the Infusoria,
though they are generally much larger and their complicated
internal structure enables them to be distinguished at a glance.
The Rhabdocoelida form a branch of the group Turbellaria,
to which the larger Planarians found in fresh water also belong.
The Turbellaria, in turn, together with the Liver-flukes and
Tape-worms, are included in the phylum Platyhelminthia
or Flat-worms.
The British marine Turbellaria have been monographed by
Prof. Gamble (12), and our President has taken an active part in
the study of the land Planarians of Australasia. The freshwater
Turbellaria have apparently received but little attention in this
country, though Prof. Gamble publishes a list of British species
in the Cambridge Natural History (14).
As the larger freshwater Planaria (Tricladida) cannot be
regarded as microscopic objects, and are therefore of no special
interest to the Club, the writer proposes, in this paper, to deal
only with the group Rhabdocoelida.
Yon Graff has written two monographs on this group, and has
devoted much time to valuable work on anatomical features ;
and it is chiefly from these sources that the information con-
tained in this paper has been derived.
The writer does not propose dealing in detail with the
anatomy, but rather to deal with the Rhabdocoels from a general
point of view, emphasising matters of particular interest to the
field naturalist.
The freshwater Rhabdocoels vary in size from 1/2 5th to half
46 H. WHITEHEAD ON BRITISH FRESHWATER RHABDOCOELIDA
an inch in length. They are generally found in ponds, lakes
and ditches, and less frequently in running water. Like many
other microscopic inhabitants of ponds, they appear in great
abundance at certain seasons of the year and then suddenly
disappear.
The body is more or less transparent, slightly flattened, and is
provided with cilia. The Turbellaria are remarkable for peculiar
secretions given off from the epidermis. These secretions are of
two distinct kinds — one a mucous fluid, and the other con-
sisting of very small solid bodies, or rhabdites, which, on coming
in contact with the water, produce mucus. Several forms of
rhabdites have been described (spindle-shaped, rod-shaped, egg-
shaped and spherical). They are formed in special glandular
cells which lie beneath the epidermis, and the rhabdites pass to
the surface by means of minute ducts.
Another interesting feature is the presence, in certain species,
of nematocysts similar to those found in Hydra.*
The Rhabdocoels are provided with a mouth, a pharynx and
an unbranched, sac-like gut. The position of the mouth varies
and affords a valuable generic character. It may lie at the
extreme anterior or in a median position anywhere along the
ventral surface as far down as two-thirds of the body length.
The excretory system consists of renal organs which are, in
some cases, somewhat complicated in structure.
The nervous system is simply, and comprises a two-lobed brain
and a pair of nerves running along the body close to the ventral
surface. In some species the pigmented eyes are clearly defined,
in others the eye pigment is scattered, and in some cases eyes
are absent.
Some of the freshwater Rhabdocoels have at their anterior
end pit-like depressions which contain cilia (PI. 4, fig. 3, cp).
The ciliated pits rest upon a group of ganglion cells which are
connected with the brain. Similar structures are found in
Nemertine worms, and some zoologists consider that this
suggests affinity between the groups. Another interesting organ
is the statocyst, which is present in some species. This consists
of a cavity containing fluid, in which is suspended a highly
* Mr. Scourfield has recently called my attention to a paper by C. H.
Martin (20) on this subject. The author shows conclusively that the
nematocysts are derived from the prey upon which the Turbellarian feeds.
A GROUP OF TURBELLARIA. 47
refractive particle of calcium carbonate — the otolith (or statolith).
The statocysts serve as organs of equilibration.
Reproduction is, in most cases, sexual. The animals are
hermaphrodite, but the male organs ripen first. The sexual
organs are very complicated, and the details of their structure
are of great value in classification. On this account it is often
impossible to determine the species of immature individuals, and
sometimes it is necessary to have specimens in both the male and
the female stages before identification can be certain. Fresh-
water Turbellaria undergo no metamorphosis, and newly hatched
individuals are similar to their parents in general appearance.
Asexual reproduction occurs only in the section Hysterophora.
A chain of individuals is formed by the development of mouths,
eyes, etc., at intervals along the body. Constriction of the body
and gut then follow, and fresh individuals are produced by
fission. The process is illustrated in PI. 4, fig. 3. Some species
which reproduce asexually throughout the year develop sexual
organs in the autumn. These produce eggs which lie dormant
through the winter.
Considerable interest has recently been aroused in certain
green or yellow cells which are found in the bodies of some
species of Turbellaria. The green cells contain chlorophyll and
are able to decompose carbon dioxide in the presence of sunlight.
Two marine species, Convoluta roscoffiensis and G. jmradoxa,
found on the coast of Brittany, have been the subjects of detailed
study, and the results have been summarised by Prof. Keeble in
a little book entitled Plant- Animals. The genus Convoluta
belongs to a group of Turbellaria, the members of which have
not, up to the present, been found in fresh water. The green cells
or zoochlorellae, as they are termed, are now regarded as algae
similar to Chlamydomonas. In the case of Convoluta it is
certain that the presence of zoochlorellae is of benefit to the
Turbellarian, and that the relationship is a true symbiosis.
Von Graff (17) mentions twenty-five species of freshwater
Rhabdocoels in which green cells have been found. The fresh-
water species containing zoochlorellae have not been well
studied, and some zoologists doubt whether there is mutual
benefit in the association. This aspect of the subject will,
however, be dealt with later.
The Rhabdocoelida live under various conditions, but generally
48 H. WHITEHEAD ON BRITISH FRESHWATER RHABDOCOELIDA —
prefer still or gently flowing water to rapid streams. One
species, Prorhynchus stag7ialis, is sometimes found on moist earth.
Many of the aquatic forms are free swimmers, and may be
captured in the net in the same way as rotifers and water-fleas ;
others live in mud. In the latter case it is best to pour a little
of the mud into a glass tank containing clear water, and to
remove any Rhabdocoels by means of a pipette. They should
be examined in a live box, and it will be found that a slight
pressure is necessary to ensure making out their internal
structure. They are very difficult to prepare in a satisfactory
manner as permanent objects, and the writer has made numer-
ous experiments with a view to narcotising them, but with
little success. Eucaine, chloroform, ether and alcohol are of no
use. The difficulty seems to lie in the fact that the rhabdites
are discharged as soon as the animal is irritated, and these, of
course, produce quantities of mucus. Moreover, the epidermal
cells get destroyed during the process. The only satisfactory
method of killing seems to be by means of some hardening re-
agent, like corrosive sublimate solution, which takes effect before
the mucus and rhabdites can be discharged. The following well-
known method is the best. The specimen is placed in a watch-
glass with a little water, the bulk of which is withdrawn by a
pipette. A drop of Lang's Fluid is then delivered from a pipette
on the side of the watch-glass and is allowed to run over the
animal. Death is almost instantaneous, and but little shrinkage
takes place. Even with this method the writer has not yet
succeeded in killing species of Mesostoma without disruption.
After remaining in Lang's Fluid from ten to fifteen minutes,
the specimens are removed to 45-per-cent. spirit. They are
afterwards passed through alcohol of increasing strength, stained
with borax-carmine and mounted in Canada balsam in the usual
way.
Some of the Rhabdocoels appear to be entirely vegetarian in
diet, and consume desmids, diatoms and unicellular algae. In
fact, care is sometimes necessary to distinguish the food from
the zoochlorellae. The latter, however, never occur in the gut.
The majority of species take animal food, which consists of water-
fleas, small worms, etc.
We may now consider a few typical species which have been
taken by the writer in the neighbourhood of London.
A GROUP OF TURBELLARIA. 49
Catenula lemnae (Ant. Dug.).
Occurs in ponds and lakes, and often appears suddenly in
considerable numbers in collections of rain-water during the
spring and summer, and disappears as rapidly as it comes.
It is white and thread-like in appearance, consisting of a chain
of 2 — 4 individuals (rarely more) and attaining a length of
5 mm. The body possesses a well-defined head lobe, which is
marked off by a slight constriction and a ring of comparatively
long cilia ; a statocyst is present. The usual mode of repro-
duction is by fission, but sexual organs are developed when the
pond or ditch begins to dry up.
Microstomum lineare (Mull.) (PI. 4, fig. 3).
This species is very similar to the foregoing, but the colour is
yellowish or greyish brown. It is usually found in the form of
a chain of zooids of which there may be as many as 18. The
colony attains a length of 8 mm. Each zooid develops a pair of
red eyes, behind which may be seen the ciliated pits. The skin
is thickly clad with cilia. No rhabdites are present, but
nematocysts, similar in form to those of Hydra, are present (20).
The figure shows the manner in which new individuals arise, and
various stages in the formation of mouths may be seen. The gut
is common to all the zooids in the chain, until fission takes place.
The writer has seen desmicls which had been swallowed for food
pass along the common gut from one zooid to another. Sexual
organs are sometimes produced, and the ripe eggs are oval in
shape and orange or dark red in colour.
This species is fairly common in stagnant or slowly moving
water. It has been found in thermal springs at a temperature
of 130° F. and also in brackish water. It moves slowly on a
surface, but is a graceful and swift swimmer.
Dalyellia viridis (G. Shaw) (PI. 4, figs. 1 and 2).
Examples of this species attain a length of 5 mm., and are
generally spinach-green in colour. The colour is due to the
presence of algal cells Which lie beneath the epidermis. The
body is truncated in front, widens towards the middle and
then tapers towards the tail. There are two bean-shaped eyes.
There is a very distinct pharynx and the gut is sac-like.
Journ. Q. M. C, Series II.— No. 72. 4
50 H. WHITEHEAD ON BRITISH FRESHWATER RHABDOCOELIDA
Specimens of this interesting Rhabdocoel were taken in one of
the ponds in Richmond Park, on the occasion of the Club's visit
on April 13th, 1912. The following week the writer took
specimens from a pond near Chigwell Row, Essex.
It was noticed that the animals had a number of eggs (in one
instance 49 were counted) in the spongy body tissue, and
individuals in this condition avoided the light. As far as could
be ascertained, no eggs were deposited by the living animals, but,
on death, the eggs were liberated on the decomposition of the
body of the parent. So far none of these eggs have hatched.
Prof. Sekera (16) of Tabor, Bohemia, succeeded in keeping
specimens alive for some time, and the following notes are taken
from the account of his observations. Young specimens were
taken in ponds in March, when ice was still floating on the
water. The animals were colourless, but as soon as they
approached maturity, and the sexual pore developed, it was
noticed that a few algal cells (zoochlorellae) had entered the
body cavity by this means. Streaks of green granules then
began to spread from this region and extend beneath the cuticle
over the whole body, until finally the animal became quite
green. (T would remark, in parenthesis, that mature specimens
show distinct lines or bands devoid of zoochlorellae.) Solid
food in the form of diatoms, rotifers, etc., was ingested during
this period. While rapid division of the algal cells was taking
place, they formed spherical or ellipsoid clusters, each group
being surrounded by a colourless membrane. The membrane
finally disintegrated and the algal cells were dispersed in narrow
irregular lines or bands. The mature zoochlorellae showed no
signs of an enveloping membrane. The animals exhibited at
this period a distinct tendency to crawl towards light (phototactic),
but sank to the bottom of the vessel at night. During the third
week eggs were formed in the body cavity. The worms at this
stage began to avoid the light and spent the whole day at the
bottom of the vessel or under vegetation. During the first week
in May the animals died off rapidly, and with the decomposition
of the body the eggs were liberated. The algal cells were set
free and continued to live, and developed an investing membrane,
then passed into a resting stage, probably awaiting an opportunity
of invading the next generation of Dalyellia.
Prof. Sekera thinks that the alga is of little or no value to the
A GROUP OF TURBELLAEIA. 51
animal in the way of providing food, his reasons being that
closely allied species, living under similar conditions, do not con-
tain algae, and that solid food is ingested after the algal cells are
fully developed. The writer hopes to investigate this question
more fully, for Sekera's argument does not seem to be quite
conclusive.
Sir J. G. Dalyell (1) wrote an account of this interesting
species in 1814, and states that it sometimes occurs in large
numbers, and then suddenly disappears. He found his specimens
chiefly in the spring, but some were found in the autumn.
Mesostoma Spp. (PL 4, fig. 4).
Some of the species of Mesostoma produce two kinds of eggs —
thin-shelled and thick-shelled. The thick-shelled eggs, which
contain a large quantity of yolk, are produced in the late summer
and lie dormant during the winter. The young hatched from
these so-called " winter " eggs, when less than half the size of the
parent commence to produce thin-shelled eggs with but little
yolk. It is probable that these eggs are unfertilised ; they are
produced in great numbers and begin to hatch in April and May.
The young hatched from these eggs attain full development
and produce thick-shelled " winter " eggs, which have been
fertilised (14).
There is some difference of opinion amongst observers as to the
precise nature of the life-cycle in this genus. See von Graff (17).
They vary in size from 3 to 15 mm. in length according to
the species and condition. They live in clear, still or slowly
flowing water and swim or creep over water-plants. Their food
consists of entomostraca, small worms, etc., which are sometimes
caught by means of slime threads.
Bothromesostoma personatum (Schm.).
Specimens of this species attain a length of about 7 mm. and
are easily identified by two white patches which look like large
eyes on each side of the "head." The rest of the body is either
grey or black. The writer has taken specimens on the leaves of
water-lilies and creeping on the surface film, at Staines and at
the East London Waterworks. The genus Bothromesostoma is
closely allied to Mesostoma, and like the latter produces both
summer and winter eggs.
52 H. WHITEHEAD ON BRITISH FRESHWATER RHABDOCOELIDA
Gyratrix hermaphroditus Ehrbg. (PI. 4, fig. 5).
This species appears to be widely distributed. It is about
2 mm. in length, is almost transparent and is a rapid and
graceful swimmer. It can easily be recognised by the com-
paratively long stiletto at the posterior extremity. This weapon,
although connected with the male copulatory apparatus, is
furnished with a gland which probably secretes a poison of some
kind and is used by the animal when attacking its prey. It has
a well-marked proboscis, behind which are two eyes. The mouth
and pharynx are situated near the middle. As a general rule,
only one egg-capsule is present, and this produces one or two
embryos.
The field is almost unworked as regards this country. Von
Graff records 110 species of Ehabdocoelida from Germany. As far
as the writer can ascertain, only 30 species have been recorded
from the British Isles. It is hoped that this short account
mav arouse the interest of some of the members of the Quekett
Microscopical Club in these interesting animals.
List of British Species.
In the following list the descriptions of the species will, unless
otherwise stated, be found in Die Silsswasserfauna Deutschlands,
Heft. 19. The initials H. W. after the localities denote that the
species has been found by the author at those places :
Sub-order RHABDOCOELA.
Section Hysterophora.
Fam. CATENULIDAE.
Catemila lemnae Ant. Dug.
Near Cork (14).
Stenostomum leucops (Ant. Dug.).
Common (14) ; Clare Is. (24) ; Staines (H. W.).
S. unicolor 0. Schm.
Clare Is. (24).
Journ. Q.M.C.
Ser. 2, Vol. XII., PI. 4,
rw
H W del.
Rhabdocoelida.
A GROUP OF TURBELLARIA. 53
Fam. microstomidae.
Microstomum lineare (Miill).
Fresh water (14) : Chigwell : Higham's Park, (H. W.) ;
" In all Scottish lochs " (19) ; near Dublin (21).
Macrostomum appendiculatum (0. Fabr.) (= hystrix,
Oe).
Stagnant water (14) ; Clare Is. (salt water) (24).
Fam. PRORHYNCHIDAE.
Prorhynehus stagnalis M. Schultze.
In Devonshire rivers (14) ; L. Lomond (19) ; Fenton
Tower, E. Scotland (9).
P. curvistylus M. Braun.
Near L. Lomond (19).
Section Lecithophora.
Fam. DALYELLIIDAE.
Dalyellia diadema Hofsten (18).
Chigwell Row (H. W.). This species appears to have been
recorded only once before, viz. in the Bernese Alps.
D. viridis (G. Shaw) (= heUuo Miill).
Generally distributed (14) ; Richmond Park, Chigwell
Row (H. W.) ; Edinburgh (9).
D. armigera (O. Schm.).
Millport (14).
D. Schmidtii (L. Graff).
Millport (14).
D. millportianus (L. Graff) (9).
Millport (9).
Jensenia agilis Fuhrm (= serotina, Dorner).
Richmond Park, Epping Forest (H. W.).
J. truncata (Abildg.).
Abundant in fresh water (14), L. Lomond (19).
Phaenocora (= Derostomum) punctatum Orst.
Theydon Bois (H. W.) ; Edinburgh (9).
Opistomum Schultzeanum Dies.
L. Lomond (19).
54 H. WHITEHEAD ON BRITISH FRESHWATER RHABDOCOELIDA
Fam. typhloplanidae.
Rhynchomesostoma rostratum (Miill).
Widely distributed (14) ; Millport, Edinburgh (9).
Typhloplana viridata (Abildg.) ( = Mesostoma viridatum
M. Sch.).
Manchester (14) : Clare Is. (24).
Mesostoma productum (0. Schm.).
Cambridge (14).
M. lingua (Abbild.).
Cambridge (14).
M. Ehrenbergii (Focke).
Cambridge (14).
M. tetragonum 0. F. M.
Cambridge (14).
M. Robertsonii L. Graff. (9).
Millport (9).
M. flavidum L. Graff. (9).
Millport (9).
Bothromesostoma personatum. (0. Schm.).
Preston (14) ; Staines, E. Lon. Waterworks (H. W.).
Fam. POLYCYSTIDIDAE.
Polycystis Goettei Bresslau.
Nr. Abergavenny, L. Lomond (19).
Fam. GYRATRICIDAE.
Gyratrix hermaphroditus Ehrbg.
Common in fresh water (14) ; Chigwell Row (H. W.) ;.
St. Andrews (salt water) (9) ; Clare Is. (salt
water) (24).
Sub-order ALLOEOCOELA.
Fam. OTOPLANIDAE.
Otomesostoma auditivum (Pless.) ( = Monotus morgiensis
et relictus Du Plessis).
Deep waters of Scottish lochs (19).
A GROUP OF TURBELLARIA. 55
Fam. BOTHRIOPLANIDAE.
Bothrioplana sp. ?
Manchester (14).
Euporobothria bohemica (Vejd.).
Tarbet, L. Lomond (19).
Bibliography.
Confined to the more important works or to papers quoted.
1. 1814. Dalyell, J. G. Observations on Planariae.
2. 1848. Schmidt, E. 0. Die Rhabdocoelen (Strudelwiirmer)
des Siissenwassers.
3. 1853. Dalyell, J. G. The Powers of the Creator, vol. ii.
4. 1865. Johnston, G. A Catalogue of the British Non-para-
sitical Worms in the British Museum.
5. 1867. Lankester, E. R. Planariae of our Ponds and
Streams. Pop. Sci. Rev., vi., pp. 388-400.
6. 1868. Houghton, W. Our Freshwater Planariae. In-
tellectual Observer, xii., pp. 445-449.
7. 1878. Jensen, O..S. Turbellaria ad litora Norvegiae.
8. 1879. Hallez, P. Contiibutions a l'histoire naturelle des
Turbellaries.
9. 1882. Graff, L. von. Monographie der Turbellarien. I.
Rhabdocoeliden.
10. 1885. Braun, M. Die Rhabdocoeliden Turbellarien Liv-
lands.
11. 1885. Graff, L. von. Article " Planarians " in Encyc. Brit.
Ninth Edition.
12. 1893. Gamble, F. W. Contributions to a knowledge of the
British Marine Turbellaria. Quart. Journ. Micro.
Science, vol. xxxiv., p. 433.
13. 1894. Fuhrmann. Der Turbellarien der Umgebung von
Basel. Revue Suisse de Zoologie.
14. 1901. Gamble, F. W. Flatworms and Mesozoa in Cam-
bridge Nat. Hist., vol. ii.
15. 1901. Benham, W. B. Lankester's Treatise on Zoology.
Pt. IV. Platyhelmia.
16. 1903. Sekera, E. Einige Beitrage zur Lebensweise von
Vortex helluo. Zool. Anz., xxvi., pp. 703-710.
56 H. WHITEHEAD ON BRITISH FRESHWATER RHABDOCOELIDA.
17. 1904-8. Graff, L. vox. Das Thierreich, Turbellaria. I.
Acoela und Bhabdocoelida.
18. 1907. Hofsten, Nils von. Studien iiber Turbellarien aus
dem Berner Oberland. Zeitschr. f. wiss. Zoologie,
lxxxv., pp. 391-654.
19. 1908. Martin, C. H. Notes on some Turbellaria from the
Scottish Lochs. Proc. Roy. Soc. Edin., vol. xxviii.,
pp. 28-34.
20. 1908. Ibid. The Nematocysts of Turbellaria. Quart.
Journ. Micro. Sci., vol. lii., pp. 261-277.
21. 1908. Southern, R. Handbook to City of Dublin. Brit.
Assoc.
22. 1909. Graff, L. von. Die Siisswasserfauna Deutschlands.
Heft. 19.
23. 1911. Ibid. Acoela, Bhabdocoela und Alloeocoela des ostens
der vereinigten staaten von Amerika. Zeitschr.
wiss. Zoologie, xcix., pp. 1-108.
24. 1912. Southern, R. Clare Island Survey. Pt. 56. Platy-
helmia. Proc. Roy. Irish Acad., xxxi.
Description of Plate 4.
Pig. 1. Dalyellia viridis, entire, x 15.
2. Chitinous copulatory organ of D. viridis, X 150.
3. Microstomum lineare, entire, x 20.
4. Mesostoma sp., entire with thin-shelled eggs, x 20.
5. Gyratrix hermaphroditus, entire, X 45. b c, bursa copu-
latrix ; c, cocoon ; c p, ciliated pit ; e, egg ; g, gut ;
m, mouth ; o v, ovary ; p, poison-sac ; p h, pharynx ;
p rf proboscis ; s t, stiletto ; it t, uterus.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 72, April 1913.
57
THE ROTIFERA OF DEVILS LAKE, WITH DESCRIP-
TION OF A NEW BRACHIONUS.
By Charles F. Rousselet, F.R.M.S.
{Read January 2%th, 1913,)
Plates 5 and 6.
Devils Lake, the largest body of water in North Dakota, U.S.A.,
is approximately 30 miles long by 5| miles wide at its broadest
part, and of very irregular shape. It receives its water from
a territory which forms an inland drainage basin extending
northwards as far as the Turtle Mountains.
From the records it appears that the level of the lake has
fallen 14 feet since 1883 (when it stood at 1,439 feet above sea-
level) and 16 feet between 1830 and 1883, making a total
recession of 30 feet in eighty years with a corresponding shrink-
age of the area of the lake. At the time of its highest level the
lake had an overflow outlet at its eastern end into Stump Lake
lying further east, and it is probable that this high-water level
was reached many times in past centuries through periods of
scanty rainfall succeeded by periods of unusually abundant pre-
cipitation. In 1910 the level of the water stood at 1,425 feet
above sea-level, but fluctuates about 4 feet between very dry
and wet periods. The lake has had no outlet for a long period,
and as the result of evaporation the water has become brackish,
the salinity increasing gradually by concentration, until at the
present time the water has a specific gravity of 1*0076 (the
sp. gr. of sea water being 1*027).
Besides common salt the water contains appreciable quantities
of sodium sulphate and magnesium sulphate, carbonate and
bicarbonate, so that it is alkaline as well as brackish, and this
no doubt accounts for the very peculiar and remarkable Rotif erous
58 C. F. ROUSSELET ON THE ROTIFERA OF DEVILS LAKE
fauna it contains, which is abundant in numbers but very re-
stricted in species.
Since 1910 a Biological station has been established on the
shores of the lake by the Legislative Assembly of the State of
North Dakota, under the control of the Biological Staff of the
State University.
At the request of Prof. R. T. Young I have at various times
examined samples of plankton collected by him in July 1910 and
May 1912, and have found therein only the following seven
species of Rotifera, the majority of them rare, strange and
unusual forms :
Triarthra longiseta Ehrenberg (a single specimen, possibly
accidental).
Pedalion fennicum Levander. {Very abundant.)
Asplanchna Silvestrii Daday. (Very abundant.)
Brachionus Midleri Ehrenberg. (Few.)
Brachionus satanicus Rousselet. (Very abundant.)
Brachionus spatiosus Rousselet. (Very abundant.)
Brachionus pterodinoides sp. nov. (Few.)
Two of these forms I have already described as new,* and
have now to introduce a third still stranger species.
The single specimen of Triarthra may have been introduced by
accident in one of the tubes.
Rotifera are essentially freshwater animals, and brackish or
salt water does not suit the great majority of species; this ex-
plains the paucity of species living in Devils Lake.
This fact does not militate against the theory of cosmopolitan
distribution of the class, on the contrary it confirms it, for
Pedalion fennicum is known from brackish lakes only in Finland,
Egypt, Central Asia, Asia Minor, etc. The presence in the lake
of the rare Asplanchna Silvestrii suggests that the " Lago di
Villa Rica," in Chile, from which it was first obtained, is a
brackish lake. Perhaps Prof. Silvestri, who obtained Daday's
* Journ. Q.M.C., Ser. 2, Vol. XL, pp. 162 and 373 (April 1911 and 1912).
WITH DESCRIPTION OF A NEW BRACHIONUS. 59
material, would be good enough to confirm or disprove this
suggestion.
Brachionus pterodinoides sp. nov. (PI. 6, fig. 1).
This new Brachionus, of which only very few specimens were
found, possesses a type of lorica new to the genus, and appears to
have done its best to try to deceive the systematic student by
making itself look as closely as possible like a Pterodina. For quite
a considerable time I was unable to decide whether the animal
belonged to the genus Brachionus or Pterodina until I found one
specimen with the foot and its two small toes protruding, which
decided the question. As will be seen on referring to PI. 6, fig. 1,
the lorica is nearly circular in shape, greatly compressed and
flattened dorso-ventrally, and possesses a foot-opening situated
just below the middle on the ventral plate, a most unusual
situation for a Brachionus, but usual in Pterodina. The dorsal
plate of the lorica is greatly extended posteriorly beyond the
foot-opening, and under this projecting cover the eggs are carried.
The lorica is smooth except anteriorly, where six small ridges
mark the continuation of the six frontal spines. The mental
edge is a nearly straight line and without indentation. As far
as could be made out in the few preserved specimens available,
the internal anatomy of this species appears to be normal. In
one specimen the wrinkled foot was extended, showing two small
pointed toes, as shown in fig. \c. The lateral antennae protrude
high up above the middle on each side.
I am greatly indebted to Mr. F. P. Dixon-Nuttall for the
three figures giving an excellent idea of the form of this new
species and new type amongst the Brachionidae.
Size of lorica, length 285 /x (l/89th inch), width 224 fi (1/1 14th
inch).
Brachionus satanicus Rousselet (PI. 6, fig. 2).
When describing this species two years ago * I had specimens
only which had been obtained in a plankton collection made in
* Journ. Q.M.C., Ser. 2, Vol. XI., p. 162 (1911).
60 C. F. ROUSSELET ON THE ROTIFERA OF DEVILS LAKE
Devils Lake in the month of July 1910, and all these had the
shape shown in the figure, with two long, curved and widely-
separated posterior spines. Last year I obtained from Prof. Young
a collection made in the month of May 1912, much earlier in the
season, when the weather in North Dakota is still cold and the
water chilly. Together with the fully developed forms in this
collection I found a much smaller form, with short posterior
spines, curved inwards and other unusual features as represented
in PI. 6, fig. 26-/. The six frontal spines and the mental edge
are identical with those of the larger specimens, but the shape of
the body and the form and size of the posterior spines are very
different, and, strangest of all, the foot-opening is situated on the
postero-dorsal side of the lorica, a quite unheard-of position in
this genus. My first impression was that these were young
animals just hatched from eggs, but this is evidently not so, for
some specimens were seen carrying their eggs at the base of the
foot on the dorsal side, and they were therefore adults reproducing
freely. I can only conclude that this represents a case of
dimorphism, possibly a winter form which gradually, in successive
generations, transforms itself into the larger form with extended
and expanded posterior spines. In saying this I do not mean
that the smaller forms (PI. 6, fig. 26-c) can themselves grow into
the form of fig. 2a, but that their offspring will in a few genera-
tions more and more resemble the larger form. Intermediate
forms between the two types figured were not seen. In order to
follow up this transformation it will be necessary to obtain
plankton collections made about twice a month throughout the
year, which at present are not available. It certainly is not
easy to see how the dorsally situated foot-opening can change
into the median posterior position of the larger form, but it is
known that in the case of some Asplanchna (A. amphora,
A. Sieboldii) the transition from humped into saccate forms and
other changes take place suddenly, from one generation to the
next, produced apparently through a change of diet and
temperature, as shown by the recent researches of Dr. Arno
WITH DESCRIPTION OF A NEW BRACHIONUS. 61
Lange * and Prof. Powers. t Should these changes in B. satanicus
be confirmed, it will be the first record of true dimorphism in the
genus Brachionus. Fig. 2e and f represent variations in the
shape of the posterior spines of the smaller form.
Fig. 2a-f were drawn from my own preparations by Mr. F. R.
Dixon-Nuttall, to whom I am greatly indebted for these accurate
and beautiful drawings.
The large form fig. 2a measures 408 /x (l/62nd inch), and
the small form 250 /x (1/1 00th inch), in both cases including
the posterior spines.
Asplanchna Silvestrii, Daday.
PI. 5, figs. 1—9.
This fine and rare species was first described by Daday in
1902,J and found by him in plankton collections made by
Dr. Silvestri in 1899 in the Lago di Villa Rica in Chile. I have
not been able to ascertain if this lake is brackish or not,
Prof. Daday having no information on this point, but the
presence therein of Pendalion fennicum seems to make it highly
probable, for the latter species has never yet been found in
fresh water.
In the collections from Devils Lake I found Asplanchna
Silvestrii in great abundance, and moreover it presented a marked
dimorphism, and even polymorphism, for all gradations from
plain saccate forms to fully developed double-humped animals
were represented in the same gathering. PI. 5, figs. 1 — 4
represent three of the forms. It is not possible for me to say
wThich of these forms appears first, or which is hatched from the
resting-egg, and what causes these changes of form. According
to the observations of Prof. J. H. Powers, of Nebraska Univer-
* Zur Kenntnis von Asplanchna Sieboldii, Zool. Anz. Bd. 38, pp. 433-441,
November 1911.
f A case of Polymorphism in Asplanchna simulating mutation.
American Naturalist, Vol. XL VI., 1912.
\ Beitrage zur Kenntnis der Siisswasser Mikrofauna von Chile. Ter-
meszetrajzi Fiizeteh, 1902.
62 C. F. ROUSSELET ON THE ROTIFERA OF DEVILS LAKE
sity, who has lately published an account of similar changes
in A. amphora found by him in a brackish pool, it is caused by a
change of diet, from vegetable to more substantial animal food,
and even cannibalistic fare. Prof. Powers found that the
animals hatched from resting-eggs were invariably saccate, and
that the humped and larger campanulate forms developed from
these.
Asplanchna Silvestrii is a very large and powerful animal, as
is shown by its ability to capture, swallow and digest the
large and vigorous Diaptomus which abound in this lake ; one
of these Copepods was seen to more than fill its stomach.
The male was also found ; it is humped, but the side humps
are not bind as in the humped female, as shown in figs. 5
and 6 ; the fertilised resting-egg is represented in fig. 9. The
jaws are of the usual type, but are different from those of any
other species of the genus, as is shown by fig. 7. The rami
are massive, and have a semi-circular cut-out near the tip,
which is peculiar ; they have also a strong basal hook and
median inner tooth. One of the rami, the one on the right
side when the basal hooks are uppermost, has a broad flange
near its apical tooth ; this serves as a stop for the opposite
tooth to prevent the two rami overlapping and interlocking.
The prominent lateral humps differ markedly from those of
other humped species, such as A. Sieboldii and A. amphora. In
A. Silvestrii these are bifid, having a constriction, more or less
pronounced, above the middle of the hump, giving it a double
rounded outline (fig. 1) ; on the dorsal side there is a pointed
hump near the middle of the body (fig. 2). In intermediate
forms the humps are less prominent until the purely saccate
form is reached (fig. 3), which in shape does not much
differ from that of A. Brightwelli. Prof. Powers has shown
that no single animal goes through these various shapes ; they
are born with the shape they possess and do not change it in
their lifetime, but their jDrogeny may have a different shape
from the parent. A young humped individual may be seen in
WITH DESCRIPTION OF A NEW BRACHIONUS. 63
the uterus of a saccate female. The change takes place more
or less suddenly from one generation to the next. The general
anatomy of A. Silvestrii follows that of other allied species,
and but few points need be mentioned. The two gastric glands
are large and kidney shaped, and are attached to the long and
rather wide oesophagus. The stomach has the usual structure
of large, dark-coloured granulated cells. The ovary has the
form of a narrow horseshoe-shaped band with a single row of
germ cells. An enlarged view of one of the lateral canals
with the contractile vesicle is given in fig. 8. The flame cells
are closely set and numerous, numbering over thirty ; the fine
tube to which they are attached adheres for some distance
to the nerve-thread of the ventro-lateral antenna on each
side.
The sense organs consist of three pairs of antennae, namely
two on the front of the head, two dorso-lateral and two
ventro-lateral in position, each ending in a rocket-shaped organ
with a tuft of stiff hairs on the outside. Two finger-like,
fleshy processes are seen, one on each side of the head close
to the corona. Daday mentions that the animal has three red
eyes, but I could discover only a single small cervical red eye,
situated on the small brain.
The male (figs. 5 and 6) is of usual structure, and has two
lateral humps, like the male of A. amphora.
Greatest size of female 1,150 /x (l/22nd inch) in length ; male
408 jx (l/64th inch) ; jaws 164 fx (l/155th inch) ; resting-egg
195 /x (1/1 20th inch) in diameter.
I am greatly indebted to Mr. Hammond for the excellent
figures of A. Silvestrii on Plate 5.
It is quite possible that farther plankton collections, and
particularly collections made amongst the aquatic vegetation
near the shores and in the bays of Devils Lake, may reveal
additional species of Rotifera, but a great crowd of freshwater
forms cannot be expected to inhabit this brackish and alkaline
lake.
64 C. F. ROUSSELET ON THE ROTIFERA OF DEVILS LAKE.
Explanation of Plates 5 and 6.
Plate 5.
Fig. 1. Asplanchna Silvestrii Daday, characteristic female with
double humps, dorsal view, x 50.
2. A. Silvestrii, side view, x 50.
3. A. Silvestrii, saccate form, dorsal view, x 50.
4. A. Silvestrii, intermediate form, ventral view, x50.
5. A. Silvestrii, male, side view, x 68.
6. A. Silvestrii, male, dorsal view, x 68.
7. A. Silvestrii, the jaws, x217.
8. A. Silvestrii, vascular system with contractile vesicle,
x 150.
„ 9. A. Silvestrii, resting-egg, x 65.
Plate 6.
Fig. la. Braehionus pterodinoides sp. nov., dorsal view, x 196.
,, lb. B. pterodinoides, ventral view, x 196.
„ lc. B. pterodinoides, side view, x 196.
„ 2a. Braehionus satanicus Rousselet. Normal type, x 180.
„ 2b. B. satanicus, small seasonal form (winter), dorsal view,
X180.
„ 2c. B. satanicus, small seasonal form (winter), ventral view,
Xl80.
,, 2d. B. satanicus, small seasonal form (winter), side view,
X 180.
„ 2e. B. satanicus, small seasonal form (winter), variation in
posterior spines, x 200.
,, 2f. B. satanicus, small seasonal form (winter), variation in
posterior spines, x 200.
Joum. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 72, April 1913.
Journ.Q.M.C.
Ser. 2,Vol.Xir,Pl. 5.
3
^-Xr"-'
1
* .
9
A. R. Hammond del.et lith.. West,>4ewma.n imp.
As plan elm a Silvestrii Dadcuy.
Journ.QM.C.
Ser. 2,Vol.XII.Pl. 6.
la
/
lb.
F.R. Dixon -Nuttall del.adnat.
A.R.Hammond lith..
West, Newman, imp.
Rotifera.
65
THE PRESIDENT'S ADDRESS.
BY-PRODUCTS OF ORGANIC EVOLUTION.
By Prof. Arthur Dendy, D.Sc, F.R.S.
{Delivered February 25th, 1913.)
Plate 7.
We are all familiar with the fact that in the manufacture
of any particular product of human industry the raw material
employed is rarely entirely used up, a more or less considerable
*•
residue generally remaining over after the process is completed.
In so far as the prime object of the manufacturer is to produce
some one special product, the residue which cannot be employed
for this purpose must be regarded as waste. It frequently
happens that this waste product is a highly deleterious substance,
the difficulty in the disposal of which may constitute a very
serious obstacle to the successful prosecution of the industry in
question. On the other hand, it also frequently happens that
what were primarily waste products may prove to have a value
of their own quite apart from the main object at which the
manufacturer is aiming. They then cease to be merely waste
products and become valuable by-products, perhaps even more
valuable than the main product itself.
Thus in the distillation of coal in a gasworks the main purpose,
that for which the machinery and apparatus are primarily
intended, is the production of gas, but coke and tar and other
by-products are also produced, all of which are now, I suppose,
applied to some useful purpose, and thus have a value of their
own. Indeed the existence of coal-tar has given rise to a whole
series of new industries, involving the production of almost endless
substances, such as the wonderful aniline dyes and so forth,
which many people will regard as far more valuable and desirable
Jourx. Q. M. C, Series II. — No. 72. 5
66 the president's address.
objects than the gas for the sake of which the coal was originally-
distilled.
The value of a by-product will naturally depend upon the
particular circumstances of the case, and what is useless, or
even harmful, under one set of conditions may be extremely
valuable under another. It may be a question of labour supply
or of transport, or it may be that the discovery of some new
process of manufacture in a totally different industry suddenly
creates a demand for a by-product that was previously almost or
entirely worthless. It is perhaps not too much to say that the
success or failure of a manufacturer in his business must in
many cases depend upon the ingenuity that he exhibits in
disposing of his by-products ; but the formation of such products
in the first instance cannot be avoided, and they may go on being
produced, and constitute a characteristic feature of the industry
for a long time, before some new factor in the circumstances of
the case may give them a special value of their own. It may
well be that this may never happen at all, and the substances
in question may simply accumulate in harmless, if unsightly,
heaps, or, on the other hand, they may become so offensive,
or even dangerous, as to render impossible the continuance of
the industry which gives rise to them.
In short, it would be difficult to exaggerate the importance
of the part played by by-products in the evolution of human
industries. Such industries are necessarily subjected to a severe
struggle for existence in ceaseless competition with one another,
and in this struggle the by-products afford abundant opportunity
for the elimination of the least fit by the process of natural
selection. The by-products, however, did not themselves arise
through any process of selection, but as the unintentional and
inevitable results of those chemical and physical changes which
accompany the manufacture of the main product.
We may thus look upon a human industry as an organism,
which undergoes a process of evolution subject to the control
of natural selection, and some of the most characteristic features
of which are to be found in its by-products. Indeed it may
often be recognised and identified by its by-products almost if
not quite as readily as by the product for the sake of which
it primarily exists.
We must not, of course, push our analogy too far, but I hope to
THE PRESIDENT'S ADDRESS. 67
be able to convince you that in the evolution of living organisms
themselves by-products have played a part not unlike that which
they have played in the evolution of industries.
You have probably already began to wonder why I should
have chosen such a subject as this for an address to a micro-
scopical club ; but the reason will now become apparent, for
I propose to endeavour to elaborate the ideas which I have
been suggesting to you by reference to organisms which have
long been favourite subjects with the microscopist, and to
characters which can only be investigated with the aid of the
microscope.
We shall perhaps find nowhere in the animal kingdom a more
exact analogy to the utilisation of waste products in human
industries than in the curious rotifer Melicerta janus. As
you are all aware, this minute but highly complex organism
builds for itself a beautiful dwelling-place out of pellets of its
own dung. I do not, however, propose to dwell upon such cases
as this, and for our present purposes I must ask you to allow
me to interpret the term waste products, or if you prefer it, by-
products— for it is obvious that the two cannot be sharply
distinguished from one another — in a less literal manner.
There is, in my opinion, no group of organisms better suited
for the illustration of the fundamental principles of organic
evolution than the Sponges. This arises from the fact that they
combine with an essential simplicity of structure an inexhaustible
variation in detail, and that this variation is to a very great extent
clearly and precisely expressed in the form of the microscopical
calcareous or siliceous spicules of which the skeleton is ordinarily
composed. Moreover, it appears that an unusual number of
connecting links have been preserved to the present day, so that
we are able to trace beautiful evolutionary series in the wonderful
spicule -forms of existing species.
Take, for example, the siliceous spicules which are so character-
istic of the Tetraxonida. These are probably all to be derived
from a primitive ancestral form or archetype (fig. 1) consisting
of four rays diverging at equal angles from a common centre,
like the axes which connect the angles of a regular tetrahedron
with its central point. The assumption of this regular geometri-
cal form by a non-crystalline substance like the hydrated silica,
or opal, of which these spicules really consist, is a very remarkable
68 the president's address.
fact, especially when we consider how very widely it is afterwards
departed from on most lines of spicule evolution. It has been
suggested that the equiradiate and equiangular tetraxon was
originally adapted to the interstices in a system of spherical
flagellated chambers arranged tetrahedrally. This seems probable
enough, but in any case we can safely take this form as our
archetype without indulging in speculations as to its origin.
If we now imagine one ray of our archetype becoming greatly
elongated we get a common form of " triaene " spicule known
as the " plagiotriaene " (fig. 2), with a long arm or " shaft "
and three short arms or "cladi," but still with all the angles
equal. If we imagine the angles which the cladi make with
the shaft to be increased, so that the cladi come to point forwards,
we get the "protriaene" (figs. 5, 5a); if the cladi extend at
right angles to the shaft we get the " orthotriaene " (fig. 3), and
if they point backwards we have the " anatriaene " or grapnel
spicule (figs. 4, 4a).
All these long-shafted triaenes are typically oriented with
the cladi at or near the surface of the sponge, and the shaft
directed centripetally inwards, so that the entire skeleton acquires
a markedly radiate arrangement. The cladi of the orthotriaenes
usually form a support for the dermal membrane at the surface
of the sponge, beneath which they are spread out tangentially,
and their efficiency as a dermal skeleton may be greatly increased
by their bifurcation (" dichotriaenes," figs. 6, Ga). In the case of
the protriaenes and anatriaenes the distal portions of the shafts,
bearing the sharp-pointed prongs or cladi, usually project for
some distance beyond the surface of the sponge, and in this
position they probably serve either to ward off the attacks of
enemies or to entangle minute organisms whose decomposition
may supply the minute organic particles upon which the sponge
depends for its food supply and which will be carried inwards
by the inflowing stream of water.
A still more remarkable modification is met with in the
" discotriaene," in which the shaft is reduced to a short peg
inserted in the middle of a flat disk formed by fusion of the
cladi. The entire spicule then assumes somewhat the form of
a carpet-nail. In the genus Discodermia we find these disco-
triaenes stuck close together all over the surface of the sponge,,
and forming an impenetrable mail-armour.
THE PRESIDENT'S ADDRESS. 69
In Stelletta vestigium, on the other hand, the cladi are reduced
to the merest vestiges, and some, if not all of them, may com-
pletely disappear, while the shaft remains greatly elongated
and forms practically the entire spicule (figs, la — Id). Possibly
the simple " oxeote " spicules of this and allied species (fig. 8)
have arisen in this manner.
An altogether different line of evolution from the primitive
tetraxon archetype appears to have given rise to the typical
oxeote spicules (figs. 9, 10) of the monaxonellid division of the
Tetraxonida. Here two of the four rays of the primitive
tetraxon have probably entirely disappeared, while the remaining
two have become extended in a straight line with one another.
In the typical " stylote " (fig. 11) and " tylostylote " (fig. 12)
spicules probably only a single ray persists, so that the so-called
organic centre is situated at one end instead of in the middle.
In many species the oxea, styles or tylostyles become ornamented
with sharp spinose excrescences (fig. 13).
In most of the cases which we have so far considered it is
easy to see that we are dealing with adaptive modifications.
The orthotriaene, dichotriaene, protriaene, anatriaene and
discotriaene are all obviously well suited for the fulfilment of
their specialised and differentiated functions, and the evolution
of these forms is more or less readily explicable in accordance
with the well-known principle of the natural selection of
favourable variations. The origin of the linear spicules of the
monaxonellid forms by complete suppression of two or three of
the rays of the primitive tetraxon is, perhaps, not so easy to
account for as is that of the triaene series from the same
starting-point. In both cases the determining factor was
probably, in the first instance, the development of a radially
arranged canal-system, requiring a corresponding radial arrange-
ment of the supporting skeleton, which could not be obtained
wTith spicules of the primitive tetraxon form. That the evolu-
tion of the necessary linear spicules has taken place along
different paths in different cases is, however, nothing to be
surprised at ; it is merely one of those instances of convergence
which are quite as common amongst sponges as amongst other
groups of the animal kingdom.
In the most primitive tetraxonid sponges, which represent
more or less closely the ancestral forms from which both
70 THE PRESIDENT'S ADDRESS.
Tetractinellida and Monaxonellida have doubtless been derived,
we still meet with some of the earliest stages of spicule
evolution. Take, for example, Dercitopsis ceylonica, collected
by Prof. Herdman in Ceylon, and described in my report on
the Ceylon sponges. Here we find the tetraxon spicule in all its
primitive simplicity (fig. 25), but associated with it we get
numerous diact spicules (figs. 26a — 26c), evidently derived from
the tetract by loss of two of the original rays, and clearly
showing, by a swelling or an angulation in the middle, that
two rays still remain. From such obvious diactine spicules as
these, transitional forms lead the way to the comparatively
large, straight oxeote spicules which occur in the same and in
many other sponges, and which no longer show any trace of
their tetraxon and tetract ancestry.
In Dercitopsis and its relations — i.e. in the Homosclerophora
— although there may be great differences as regards the size
of the various spicules, yet we cannot, as in most of the higher
groups, sort these spicules out into two distinct categories —
megascleres and microscleres — for innumerable gradations exist
between large and small.
In the course of further evolution, however, the distinction
between megascleres, or skeleton spicules, and microscleres, or
flesh spicules, becomes very strongly marked. Both have
doubtless had a common origin in the ancestral tetraxon
archetype, but whereas the former are obviously adapted as the
principal skeletal elements, and are arranged accordingly in
the sponge, the latter are usually scattered at random through
the soft ground substance like plums in a pudding, and neither
in form nor arrangement show any evident adaptation to the
requirements of the organism.
Indeed, the microscleres are usually so extremely minute,
requiring high powers of the microscope to make out their
true form, that is impossible to believe that their presence can
exercise any important influence upon the well-being of the
sponge. Still less is it possible to believe that the particular
shape which they may assume, which is often highly remarkable,
can be of any consequence to their possessor. There are, of course,
exceptions to this, as to every generalisation, and sometimes we
find microscleres forming a dense protective external crust, as
in the case of the " sterrasters " of Geodia, or projecting into the
THE PRESIDENT'S ADDRESS. 71
inhalant canals, where they may perhaps serve to filter the
incoming water and guard against parasites, as in the case of
the " sigmata " of Esp>erella murrayi ; but in the vast majority
of cases it is impossible to assign any value at all to the
presence of microscleres. Indeed, the numerous species of
horny sponges seem to get on quite as well without these
bodies.
Nevertheless we find that the microscleres, when present,
are characterised by very definite and constant forms, and many
of them are amongst the most beautiful and wonderful objects
that come under the observation of the microscopist. So constant
and characteristic are they that they afford by far the most
convenient and most reliable data for the classification of the
tetraxonid sponges. Particular species, and even particular
genera and families of these sponges, are characterised by the
presence of highly specialised forms of microscleres, and in the
case of species the characteristic form is almost invariable.
There can be no doubt that the microscleres have undergone
an evolution along definite lines, and one species of a genus is
commonly distinguished from another by differences in the
shape of these spicules, which, though constant, appear at the
same time to be utterly trivial — as, for example, the difference
in the shape of the teeth at the small end of the " isochelae " in
Cladorhiza pentacrinus (figs. 23, 23a) and Cladorhiza (?) tridentata
(figs. 24, 24a). There may be several kinds of microsclere in
the sponge, all characteristic of the species, but a single sponge
may contain many thousands, or perhaps millions, of the same
kind, all exactly alike in shape and size except for an occasional
individual variation such as occurs in all organisms.
The shape of the microscleres appears to be quite independent
of their position in the sponge, and must obviously be attributed
to some specific peculiarity of the ovum from which the sponge
developed. It is clearly of a blastogenic and not a somatogenic
character, and it is usually much more remarkable and quite
as constant as that of the megascleres of the same species.
The microscleres of the tetraxonid sponges may be divided
into two categories, termed astrose and sigmatose respectively.
The former (figs. 14a — 14A) may be derived from the tetraxon
archetype by multiplication of the rays — due apparently to
meristic variation — accompanied usually by diminution in size of
72 the president's address.
the whqle spicule ; at the same time the rays may become spiny
or branched in a variety of ways, or even soldered together to
form a solid siliceous ball (Geodia).
The sigmatose microscleres are more remarkable and more
constant in form. They are essentially linear spicules, and
appear to be derived from minute diactinal oxea. These may be
straight (" microxea," fig. 15) or bow-shaped (" toxa," figs. 16, 18a,
186), or their extremities may become bent over to form hooks
(" sigmata," figs. 17a, 176, 19). A very peculiar modification of
the sigmata is found in the " diancistra " (fig. 21), which often
resemble nothing so much as pocket-knives with the blades half
open. From the sigmata have also doubtless arisen the " chelae," *
characteristic of the family Desmacidonidae, and, in my opinion,
the most wonderful of all sponge spicules. Three different chelae
are shown in figs. 22 — 24a.
A typical chela consists of a curved shaft, bearing a number,
commonly three, of recurved teeth, resembling the flukes of an
anchor, at each end. The flukes are sometimes expanded into
thin blades, and so also may be the shaft. Sometimes the flukes
at the two ends of the spicule are equal in size (" isochelae,"
figs. 22, 22a), sometimes those at one end are larger than those
at the other (" anisochelae," figs. 23 — 24a), while in the genus
Melonanchora a very curious effect is produced by the meeting
and fusing of opposite flukes of an isochela at the equator of
the spicule. Minute differences in the form and number of the
flukes and the shape of the shaft appear to be constant, at any
rate within the limits of a species ; indeed, the very numerous
species of Desmacidonidae are to a large extent distinguished from
one another by these characteristics (compare figs. 23, 23a, and
24, 24a).
The same constancy of form is to be observed in the sigmata,
although here there is less scope for specific differences. In
both cases the spicule, instead of remaining smooth, may become
more or less roughened by the development of minute projections.
This is shown, for example, in the sigmata of the genus Par-
esperella (fig. 20), where a row of small projections, like the teeth
* It is perhaps unnecessary to discuss here the evidence for believing
that the chelae have arisen from sigmata. It is derived partly from the
development of the chelae themselves and partly from the occurrence of
intermediate forms.
THE PRESIDENT'S ADDRESS. 73
of a saw, occurs at each end of the shaft, just where it bends
round.
Now it appears to me quite idle to argue that minute differ-
ences in the form of the microscleres, such as I have just described,
are of any importance to the sponge in whose soft tissues these
microscopic spicules are scattered without order or arrangement.
Nevertheless they constitute, as I have already said, constant
specific characters, and have undoubtedly arisen by some process
of evolution, one form Lading to another just as in the case
of any other characters. Such characters are, of course, by no
means confined to sponge spicules ; they may be more or less
exactly paralleled, for example, in the frustules of Diatoms, the
shells of Foraminifera and Kadiolaria, and the calcareous spicules
of Holothurians. Natural selection cannot be directly respon-
sible for their origin. How, then, are they to be accounted
for?
Before attempting to answer this question let us inquire how
a microsclere actually arises in the sponge. It appears that,
from an early stage in embryonic development, certain cells,
known as scleroblasts, or mother-cells, are set aside for the
purpose of spicule-formation. These mother-cells have the power
of extracting silica in solution from the sea-water which circu-
lates through the sponge, and depositing it in the form of solid
opal, and in the particular shape characteristic of each spicule.
Each separate microsclere arises thus in the interior of a single
mother-cell. Let us examine a little more closely the conditions
under which it is deposited.
The mother -cell is, of course, a nucleated mass of protoplasm,
and it appears to be bounded on the outside' by a more or less
definite cell -membrane. The spicule, at any rate in the case
of sigmata and chelae, appears to be deposited on the inner
surface of this membrane, and this fact probably explains why
it is curved. If we assume, as seems probable, that the mother-
cell continues to grow while the spicule is being deposited, and
that the spicule is adherent to the cell-membrane, then we may
further suppose that the increasing tension and expansion of the
latter may cause the thin siliceous film to split into flukes or
teeth. Probably, then, the form of the spicule is largely due to
mechanical causes. We cannot, however, explain the minute
details of structure so simply as this, for why should the chela
74 the president's address.
of one species have always three flukes and that of another
always more ? Why should the two ends in some cases be equal
and in others unequal 1 Why should the teeth at the small end
sometimes be shaped as in fig. 23 and sometimes as in fig. 24 ?
and why should some be roughened with spines and others not ?
We must, I think, assume that these minute differences are
dependent upon minute differences in the constitution of the
protoplasm of which the mother-cell is composed. It may be
a question of the chemical and physical composition of the
cytoplasm in which the spicule is actually deposited, or it may
be that the nucleus exerts some direct controlling influence
upon the form of the spicule, of the nature of which we know
nothing.
At any rate we can hardly be wrong in attributing specific
differences of spicule-form to corresponding differences in the
constitution of the mother-cells by which they are secreted. The
remarkable thing is that such differences should be so constant,
not only throughout hundreds of thousands of mother-cells in
the same sponge, but throughout the mother-cells of all the
individuals of the same species. We can only suppose, as I said
before, that this constancy depends upon some constant peculiarity
of the germ-plasm from which all the cells of the individual and
all the individuals of the species originate. Obviously the ferti-
lised ovum must contain within itself the potentiality of pro-
ducing, amongst other things, all the different kinds of spicules
which may happen to characterise the particular species to which
it belongs. As development goes on differential divisions must
take place whereby all the different kinds of cells of which the
adult sponge is composed are segregated, and each mother-cell
must ultimately retain the power to secrete only one particular
kind of spicule. Now there is strong reason for believing that
differential cell-division is effected always by the complex process
of mitosis or karyokinesis, which concerns chiefly the chromosomes
of the nucleus, and hence I think we may pretty safely conclude
that specific differences in the form of the microscleres must
depend upon differences in the constitution of the nuclei of the
mother-cells, or, in other words, that the nuclei of the mother-
cells determine to a large extent the form of the microscleres.
There appear, in short, to be three secondary factors concerned
in the production of any particular form of microsclere : (1) the
THE PRESIDENT'S ADDRESS. 75
nature of the material (opal) of which the microsclere is com-
posed ; (2) the nature of the medium in which it is deposited,
viz. the colloidal cytoplasm of the cell ; and (3) the presence of
the cell-membrane, by which the growth of the spicule is to some
extent restrained and guided. All three are, however, doubtless
dependent upon the hereditary constitution of the mother-cell
(including, of course, its nucleus), for while the mother-cells in
siliceous sponges secrete hydrated silica, those of the Calcarea
secrete carbonate of lime, and so on.
We have next to inquire how it is that, if the specific forms
of sponge microscleres are of no importance to the sponge, such
very remarkable forms should ever have arisen in the course
of evolution. We have to remember in this connection that we
are dealing not merely with a few isolated and unrelated forms,
but with progressive evolutionary series along lines as definite
as any other lines of evolution with which we are acquainted,
and which certainly seem to require some directive force to
explain them. If we were dealing with adaptive characters we
should at once say that the result was due, as in the case of the
megascleres, to the natural selection of small, fortuitous, favour-
able variations ; but the fact that the characters in question are,
for the most part at any rate, not adaptive, seems, at first sight
at any rate, to rule natural selection out altogether.
It might be suggested, however, that the solution of the
difficulty is to be found in the well-known principle of correlation.
In accordance with this idea certain characters of an organism
are inseparably linked together with other characters in such
a way that any variation in the one must be accompanied by
a corresponding variation in the other, though the reason why
such characters should be so linked together is often by no means
obvious. To upholders of such a view as this the analogy of
by-products, upon which I laid so much stress at the beginning
of my address, may, I think, prove useful. Although I doubt
whether the hypothesis of correlation is adequate to meet the
present case completely, it certainly seems worth while to
examine it a little more closely.
I may illustrate my meaning by reference to the action of a
few drops of acid upon an alkaline solution of litmus. Two per-
fectly distinct results will be produced. The solution will become
acid and it will change from blue to red. You may desire for
76 the president's address.
some special purpose to produce one of these results only, but
they are inseparably connected and you cannot have one without
the other. You cannot have the result aimed at without having
also the by-product.
Now suppose some change in the constitution of the germ-
plasm of an organism to give rise to two modifications in the
developing soma or body. We may call the change or modi-
fication in the germ-plasm GA and the modifications in the soma
SA and Sa. SA and Sa will be inseparably correlated with one
another through GA, though — as for example in the case of
white tom-cats with blue eyes, which are said to be generally
deaf — the connection between them may appear to be quite
arbitrary.
Suppose further that SA proves to be a useful character and
Sa a useless one. Then, under the influence of natural selection,
SA will be preserved and may ultimately develop into a very
perfect adaptation ; but, if so, GA must also undergo further
modification, and this modification will likewise affect Set, which will
therefore keep pace, so to speak, with SA. Thus a non-adaptive
character (S«) may undergo progressive evolution, which, though
in reality indirectly controlled by the action of natural selection,
may appear to be guided by some mysterious vital force or
entelechy.
Now suppose further that as a result of some change in
the conditions of life, or merely as the result of its progressive
evolution in some particular direction, So- in turn acquires some
value in the struggle for existence. Natural selection will, in
future, favour its further development directly, and what was
at first a mere by-product becomes an adaptive character. Thus
adaptive characters may perhaps become linked together in
groups, the existence of each group being dependent on some
particular property of the germ-plasm through which all the
members of the group are connected.
At the same time non-aclaptive characters may persist side
by side with adaptive ones, and even harmful variations may
persist if their injurious effects are counterbalanced by useful
characters with which they happen to be correlated and which
cannot exist without them. Inasmuch, however, as two useful
characters are more valuable than one, natural selection will
tend to favour the correlation or linking together of adaptive
THE PRESIDENT'S ADDRESS. 77
characters, and this is perhaps the reason why, in the higher
organisms, non -adaptive characters are less frequently met with
than in lower forms. Moreover, the effect of natural selection
will tend to become cumulative and the rate of evolution corres-
pondingly increased.
It may be objected that even in the highest organisms
characters often vary independently of one another, but who
knows how many characters are really involved in each such
variation ? Moreover, it by no means follows from what has
been said above that new characters, whether valuable or
otherwise, may not arise singly and remain quite independent
of others.
In any case the principle of correlation could hardly help us
to explain the specific forms assumed by sponge microscleres, or
indeed the exact nature of any non-adaptive character ; it could
only help to explain why such characters should exist at all and
why they should undergo progressive evolution.
If it be asked, what are the adaptive characters with which,
in our own particular case, the non-adaptive characters of
the microscleres are supposed to be correlated ? it must be
admitted that this question cannot — at any rate at present — be
answered, but it would be sufficient for the general argument if
it were granted that a modification in the constitution of the
germ -plasm which gives rise to a useful character may at the
same time give rise also to a useless one, or perhaps even to
many useless ones.
The question, why are the specific forms of sponge microscleres
what they are1? is probably one that will have to be answered,
if it ever is answered, by the chemist and physicist rather than
by the mere biologist ; or perhaps by that happy combination
of chemist, physicist and biologist whose advent is so much
to be desired. I have suggested that the form is probably
determined by the hereditary constitution of the mother-cell,
including its power to select silica as the raw material to be
worked up, but this is no more than to say that the nature of
the product turned out by a factory depends upon the character
of the work-people employed and of the machinery and raw
material with which they have to deal. In the case of our
microscleres we want to know a great deal more about the
nature of the machinery and the manner in which it is controlled
78 the president's address.
before we can hope to reach even an approximate solution of the
problem.
Some light may perhaps be thrown on the subject by ex-
periments such as those of Leduc and others upon artificial
osmotic growths. Leduc, in particular, has succeeded in pro-
ducing very interesting growth-forms by the osmotic action of
various chemical reagents in solution. Some of these forms bear
an extraordinary resemblance to the forms of living organisms.
I do not, of course, attribute much importance to the particular
forms produced in this manner as explaining the particular
forms of any living organisms. What they demonstrate is that
purely chemical and physical causes may give rise to more or less
definite and at the same time non -crystalline forms in colloidal
media, and though none of the forms as yet produced come
anywhere near our sponge-spicules in symmetry or sharpness of
definition, they certainly seem to indicate a hopeful line of
inquiry. The particular form produced depends upon the nature
of the reagents employed and upon the conditions under which
the experiment is carried out. If these always remain constant
we may assume that the osmotic growth will always have the same
form, but probably with the means at our disposal it would be
impossible to produce exactly the same result twice over. The
remarkable thing about the sponge microscleres is that within
the limits of the same species the same results very often are
exactly reproduced, or at any rate so exactly that we are unable
to distinguish between them. I suggest that these results are
produced by chemical and physical causes, involved in and
controlled by the hereditary constitution of the mother-cell,
and that any modification of this hereditary constitution must
give rise to a corresponding modification in the results. Further
than this I fear we cannot at present venture.
It has frequently been objected to the theory of natural
selection that, however much useful characters may be en-
couraged and fostered in the struggle for existence, it cannot
account for the first appearance of such characters. This appears
to me to be a very fair criticism. It seems to me, also, very
misleading to speak of the origin of species by natural selection,
for specific characters throughout the animal and vegetable
kingdom are, I believe, generally non-adaptive, and therefore
cannot be directly due to natural selection. This is certainly the
THE PRESIDENT'S ADDRESS. 79
case with the specific characters of sponges, which, as we have
seen, depend for the most part upon trivial microscopical differ-
ences in the shape of the spicules.
Without entering upon the vexed question of the relation
between somatogenic and blastogenic characters, we may assume
in our ignorance that such characters as those which we have
been discussing arise fortuitously in the germ-plasm, and that
it is a mere chance whether or not they may prove to be of any
value to the organism. If they are valuable, natural selection
will foster and encourage them ; if they are not, they may
nevertheless persist for many generations unless too injurious to
their possessors. If linked by correlation with useful characters
they may be indirectly fostered by natural selection, and un-
dergo a course of evolution parallel to that of their correlative
characters. Although they may be useless at first, they may
acquire some special value under new conditions of life, or in
the course of their evolution under the old conditions, and then
natural selection will begin to act upon them directly.*
Possibly all the characters which an organism exhibits, with
the important exception of those which are due to the effects
of use and disuse of organs, or to the response of the
organism in some other way to the direct action of the environ-
ment, have first arisen as by-products of the complex chemical
and physical processes upon which the life of the organism
depends.
There is one more aspect of the problem to which I should like
* Having been asked to give a definite example of a character which,
at first useless, has ultimately acquired an adaptive value, I suggest the
pattern of the venation on the front wings, or tegmina, and on the leaf-like
outgrowths of the abdomen in the leaf-insect Pulchriphyllium cvurifoliuvi.
This venation so closely resembles that of a leaf as greatly to increase
the remarkable protective resemblance which undoubtedly enables the
insect to conceal itself effectively from its enemies. The mere pattern
of the venation in the more primitive and typical Orthoptera can hardly
have had any selective value. Of course the venation itself must always
have been useful, both for supporting the wings and for supplying them with
air, etc. ; but as regards the pattern which the venation makes (which is
the character to which I refer) one type of arrangement would seem to
have been as good as another until it acquired a special adaptive value
as a factor in bringing about protective resemblance to a leaf, and then
doubtless the pattern evolved under the influence of natural selection until
it reached its present degree of perfection.
80 THE PRESIDENT'S ADDRESS.
to direct your attention before concluding. The constancy in
the specific form of the microscleres of the Tetraxonida appears
to be much greater in the case of the sigmatose than in that of
the astrose series, and in the former at any rate seems to point
to the different modifications having arisen as mutations rather
than as fluctuating variations. This would, I think, be quite
in harmony with the views which I have been endeavouring to
express. A mutation, however small it may be, is believed
to be due to some change, apparently sudden, in the constitution
of the germ-plasm, which may then remain without further
alteration until another mutation occurs. To say that the
change in question is probably of a physico-chemical character
seems almost a truism ; but if it is so it seems only natural to
suppose that such a modification, transmitted by cell-division
to all the mother-cells of a particular kind, may affect in a
uniform manner the form of all the microscleres deposited in
these mother-cells, just as a change in the character of the
reagents employed will affect the form of osmotic growths ex-
perimentally produced. If this view be correct, we must suppose
also that any adaptive modifications with which the modifications
of the microscleres may possibly be correlated must also have
arisen as mutations. I see no objection to such a supposition,
for mutations, if they occur sufficiently frequently, may be quite
as valuable from the point of view of natural selection as small
fluctuating variations.
We do not, of course, know what may be the cause of the
modification in the constitution of the germ-plasm that gives rise
to a mutation, but there is some reason to believe that it may
be due either to the permutations and combinations of ancestral
characters which take place in the maturation and fertilisation
of the germ-cells, or to the influence of some change of environ-
ment upon the germ- plasm. If the characters of sponge spicules
are really of the nature of mutations it should be possible to
obtain Mendelian results by hybridisation, and I hope that
at some time in the future experiments may be made with this
object in view. The difficulties in the way of carrying out
such experiments would probably, however, be very great, and
we should require to know a great deal more than we do about
the breeding habits and life-history of sponges before we could
hope to bring them to a successful issue.
33
33
33
3)
33
33
33
THE PRESIDENT'S ADDRESS. 81
Description of Plate 7.
Fig. 1. Ideal primitive tetraxon.
2. Plagiotriaene of Ecionema carteri, x 52.
3. Orthotriaene of Pilochrota homelli, X 52.
4. Anatriaene of Tetilla poculifera, X 52.
4a. Cladome of 4 x 230.
5. Protriaene of Tetilla pocidifera, x 52.
5a. Cladome of 5 x 230.
6. Dichotriaene of Ecionema laviniensis, x 52.
„ 6a. Cladome of 6, seen from above, x 52.
,, la-Id. Ends of triaenes of Stelletta vestigium, with reduced
cladi, x 230.
,, 8. End of oxeote of Stelletta vestigium, x 230.
,, 9. Angulated oxeote of Pachychalina subcylindrica, x 360.
„ 10. Straight oxeote of Reniera pigmentifera, x 360.
,, 11. Style of Axinella halichondrioides, x 230.
„ 12. Tylostyle of Hymedesmia curvistellifera, X 230.
„ 13. Spined tylostyle of Myxilla tenuissima, x 530.
,, 14a-14A. Astrose microscleres of Xenospongia patelliformis,
X 530.
„ 15. Microxeote microsclere of Desmacella tubidata, x 230.
„ 16. Toxiform microsclere of Gellius angulatus var. canalicu-
lata, x 230.
„ 17a, lib. Sigmata of Gellius angulatus var. canalicidata, x 230.
(Note the angulation of the spicule, suggesting
derivation from a diactinal microxeote, such as is
represented in figs. 26a-26c.)
18a, 186. Toxa of Toxochalina robusta var. ridleyi, X 230.
19. Sigma of Desmacidon reptans, X 512.
20. End of sigma of Paresperella serratohamata, x 530.
21. Diancistron of Vomerula or Hamacantha, x about 200.
22. Isochela of Esperiopsis pulchella, front view, x 284.
,, 22a. Side view of same, x 284.
„ 23. Anisochela of Cladorhiza jientacrinus, front view, x 700.
,, 23a. Side view of same, x 700.
„ 24. Anisochela of Cladorhiza (?) tridentata, front view,
x 360.
„ 24a. Side view of same, x 360.
Journ. Q. M. C, Series II.— No 72 6
35
33
33
J3
82 the president's address.
Fig. 25. Primitive tetraxon (calthrops) of Dercitopsis ceylonica,
x 230.
„ 26a-26c. Small oxea of Dercitopsis ceylonica, x 230. (Oxea
four or five times as large occur in the same
sponge.)
(Figs. 2-186, 20, 25-26c, from Dendy's Report on the Sponges
collected by Prof. Herdman at Ceylon in 1902. Figs. 19, 21, 22,
22a, 24, 24a, from Ridley and Dendy's Report on the Challertgo
Monaxonida. Figs. 23, 23a, from Dendy in Ann. <& Mag. Nat.
Hist., Ser. 5, vol. 20, PI. xv.)
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 72, April 1913.
Journ.dM.C
Ser.2yol.XlI
Spicules of Tetra-xorud Sponges.
83
ON FIVE NEW SPECIES OF BDELLOID ROTIFERA.
By David Bryce.
{Read March 2oth, 1913.)
Plates 8 & 9.
The five species of which descriptions are furnished in the present
paper have been known as distinct forms for many years past,
although their distinguishing characteristics have not hitherto
been gathered into the formal diagnosis which constitutes scientific
baptism. Four of them belong to that important section of the
Philodinidae in which the food is formed into pellets after passing
through the mastax, and are assigned to the genus Habrotrocha.
The fifth species belongs to the more numerous section of the
same family in which the food is not at any time agglutinated
into pellets, and being oviparous and possessed of three toes is a
member of the genus Callidina, as now restricted.
Under the name of Habrotrocha munda, I describe the form to
which T referred in some remarks upon the identity of Callidina
elegans Ehrbg., appended to my paper on " A New Classification
of the Bdelloid Rotifera," * as having been wrongly identified as
that species by Hudson and Gosse and by other writers. I have
endeavoured in that place to show as clearly as possible my
reasons for the belief that this form cannot be that which Ehren-
berg described ; and inasmuch as none of the various correspondents
who have addressed me with regard to my classification have
advanced a view contrary to my own in this matter, I think
that this victim of mistaken identity may now be established on
a firmer and less assailable basis.
This species is the most common of the few pellet-making forms
which have their usual habitat in ponds and ditches. In fresh
gatherings it may frequently be seen swimming vigorously with
its head slightly deflexed, or perhaps marching about at a great
* Jaimi. Q. M. C, Ser. 2, Vol. XI., p. 61.
84 D. BRYCE ON FIVE NEW SPECIES OF BDELLOID ROTIFERA.
pace, and will often attract attention from the bright reddish
colour of the stomach wall. On closer examination it may be
readily recognised from the peculiar shape and pose of the spurs,
which are quite distinctive, and from the many-toothed rami.
Under more natural conditions, it takes shelter in any convenient
recess among debris or in leaf axils, and there makes its home,
protruding the head and neck when it desires to feed.
The second species, Habrotrocha torquata, has similar many-
toothed rami, but in several other respects differs distinctly from
H. munda. I believe that in some quarters it has also been
accepted as Callidina elegans Ehrbg., probably on account of the
rami. Unlike H. munda, it is never found in ditches or ponds,
but has its habitat usually in mosses growing in positions fre-
quently wet. The spurs are of simple form and the stomach wall
is never of reddish tint. It has not been observed to seclude itself
in any way and is of comparatively quiet habit. Its specific
name was suggested by a curious but illusory appearance in some
positions of an annulus encircling the expanded corona.
The third of the pellet-making species, Habrotrocha spicida, is a "
rather smaller form, which has the, so far, unique distinction of a
single spine of small size placed on the pre-anal segment on the
median dorsal line. When the body is contracted, or when the
animal is seen in lateral view, this spine is sufficiently obvious,
but at other times it is most easily overlooked. In my own
experience this Bdelloid has only occurred in hilly country in
elevated positions, but I learn from Mr. James Murray that he
has also met with it in lowland habitats.
The fourth species, Habrotrocha ligida, is one of those puzzling
forms which can only be recognised with certainty when it is feed-
ing. It is mainly distinguished by the possession of a small fleshy
tooth, which stands erect in front of the narrow sulcus between the
two pedicels of the corona, difficult to discern except in direct dorsal
view. In other respects it offers little to remark.
For my earliest knowledge of the new Callidina, I am indebted
to my esteemed correspondent the late Forstmeister L. Bilfinger,
D. BRYCE ON FIVE NEW SPECIES OF BDELLOID ROTIFERA. 85
of Stuttgart, who sent to me, as long ago as 1894, a sketch of the
animal together with some moss in which it occurred. I have
therefore given it the specific name Bilfingeri, in honour and in
grateful appreciation of a most courteous correspondent and of a
painstaking and careful observer of the Rotifera. The type form
of this species is marked by a series of lateral and dorsal knob-
like prominences on the posterior half of the trunk. As in most
other species with such knobs or with spines, the presence of these
ornaments is not constant, and occasional examples are found in
which some or even all the typical prominences are absent.
Habrotrocha munda sp. no v. (PI. 8, fig. 1).
Specific Characters. — Corona moderately wide, exceeding collar ;
pedicels with dorsal inclination ; discs more strongly inclined in
same direction. Under lip relatively high, centrally prominent
and spoutlike, Dorsal antenna long. Rami with seven or
more fine teeth. First foot joint with dorsal prominence. Spurs
resembling caudal processes of Chaetonotus.
In general build and in the somewhat " smothered " appearance
of the corona, due in this case to the shortness of the pedicels and
to the very oblique setting upon them of the trochal discs, this
species has a certain resemblance to Habrotrocha torquata, but
can usually be distinguished from it by the shape of the spurs,
which in typical specimens have a very characteristic moulding
and pose. In the normal or extended position, the body is spindle-
shaped, distinctly larger about or a little behind the centre, and
smaller at either extremity, and rarely exceeds 320 /x in length.
While the rostrum is shorter and thicker than usual, the head
and neck are only moderately stout, the trunk being distinctly
larger (sometimes almost swollen when well fed), the lumbar
segments short and tapering rapidly to a relatively small and
slender foot of (I think) three segments. When creeping, the
dorsal and lateral longitudinal skin-folds are usually well marked.
In adult examples the stomach wall is frequently of a vivid
reddish colour, and the lumen of the stomach is usually crammed
86 D. BRYCE ON FIVE NEW SPECIES OF BDELLOID ROTIFERA.
with obvious food pellets. The first foot segment has a median
dorsal prominence of moderate height, rather wider than long,
and best seen in lateral view. The second segment has the very-
characteristic spurs, which always suggest to me the caudal
processes of the common form of Chaetonotus. They are longer
than is customary among pellet-making species, frequently
measuring 14 to 15 /x in length, but are sometimes much shorter.
Near the base they are swollen on the inner side, and closely
approximate. About mid-length they suddenly diminish in
thickness and are thence produced to rather acute points. The
outer side of each is nearly straight, and they are held at a
slightly divergent angle. The three toes are difficult to see, but
the terminal pair (and I think the dorsal toe" as well) are
moderately long and acute. The dorsal antenna is sometimes
quite 25 fx long and is carried much as in Rotifer macrocerost
being inclined backwards when the animal is creeping about, and
directed more or less forward when it is feeding.
The corona attains a width of about 45 li. The trochal discs
are separated by a shallow furrow, which narrows to a mere
notch as it nears the ventral side. On that side accordingly the
principal wreath is almost uninterrupted, and in place of the
customary appearance in front view of two distinct " wheels ''
there is rather that of a toothed band passing rapidly round a.
single transversely elliptic course, distinctly broken on the dorsal
side and only slightly indented on the ventral. In lateral view
it is seen that the pedicels are dorsally inclined, short and
obliquely truncate, so that the trochal discs are still more inclined
towards the dorsal side. The under lip and mouth margins are
high in relation to the discs, and the former centrally prominent
and spout-like as in Habrotrocha angusticollis, but in a lesser
degree. The upper lip is usually hidden by the reverted rostrum.
So far as I have been able to discern, it rises moderately towards
the centre and is neither bilobed nor reflexed. The rami are
about 19 fx in length, somewhat triangular in outline, and have
each at least seven very fine teeth.
D. BRYCE ON FIVE NEW SPECIES OF BDELLOID ROTIFERA. 87
Habrotrocha munda occurs most frequently in pools, especially
when water-mosses and anacharis are present. I have also found
it occasionally in sphagnum and in confervae, both in floating
masses and in the growth upon submerged stones. In suitable
situations it makes for itself a rough case or nest of the same type
as that produced by Rotifer macroceros.
It is of cosmopolitan distribution. I have noted it for
England, Scotland, Germany (Baden, Black Forest, Wurtemberg,
Stuttgart), Cape Colony.
Habrotrocha torquata sp. nov. (PL 8, fig. 2).
Specific Characters. — Of medium size and stoutness. Corona
equal to or rather exceeding collar ; pedicels short, distinct ;
trochal discs more or less dorsally inclined. Upper lip moderately
high, undivided but centrally slightly reflexed ; under lip
unusually high, yet scarcely prominent. Dorsal antenna rather
long. Kami with six or more fine teeth. Spurs short, divergent,
conical.
When creeping about, H. torquata is somewhat difficult to
recognise, as it lacks any conspicuous peculiarities of form, colour
or size. It is perhaps most usefully described by comparison with
other species of the same genus having similar many-toothed
rami. The body is of moderate dimensions, less spindle-shaped
than in H. munda, but less parallel-sided than in H. elegans
(Milne). The rather short foot is longer and more distinct than
in the latter species, but is less so than in H. constricta (Duj.).
The spurs are simple short cones of moderate stoutness, and are
held at almost a right angle, differing thus from the slighter and
widely divergent spurs of H. constricta, the short, peg-like, very
slightly divergent spurs of H. elegans (Milne) and the com-
paratively long moulded spurs of H. munda. In most examples
the stomach is not obviously tinted, but is occasionally of a
yellowish colour, yet never of the reddish shade frequent in
H. munda, H. auricidata, and other species.
In habit it resembles H. constricta ; that is to say, it lives in the
88 D. BRYCE ON FIVE NEW SPECIES OF BDELLOID ROTIFERA.
open and is not a dweller in the shelter afforded by natural or
contrived gatherings of dirt particles or debris like H. elegans
(Milne) and H. munda. I have never met with it in pools, but
usually in mosses (not sphagnum) growing in wet positions.
When the corona is displayed, it is seen to have a quite unusual
appearance. As in H. munda, the trochal discs are inclined
towards the dorsal side, but in a varying degree, and are
separated by a furrow deeper than in that species. The upper
lip rises in a broad rounded lobe which is centrally bent back,
leaving visible the fleshy connection, or nexus, between the short
pedicels. On the ventral side the under lip rises unusually high,
and thus in dorsal view, the collar, which passes round the
pedicels on either side and merges gradually into the under lip,
has an obliquely upward direction, not obliquely downward as
customary. This results in the optical presentments of the
rapidly beating cilia of the secondary wreath (those lining the
collar and passing round to the mouth), and of the cilia of the
principal wreath (those of the trochal discs), being to some extent
commingled, and there is the appearance of an annulus or ring
passing round the trochal discs immediately below their margins.
When the discs are seen so that their planes are nearly
coincident with the line of sight, they appear to have deeply
grooved margins, but the exact appearance varies with the angle
at which they are viewed. Whether the appearance be that of a
ring or of discs with deeply grooved margins, it is in my opinion
purely an optical effect arising from the mutual interference of
the light rays from the two wreaths of cilia.
The high under lip is unusually flat and inconspicuous ; the
lateral margins of the mouth are scarcely thickened and the
mouth cavity is small as compared with that of other Philo-
dinidae. When feeding the lumbar plicae are well marked.
The foot represents about one-ninth of the total length. It
has four joints, the first having dorsally a distinct thickening of
the hypodermis.
In the confinement of a small cell H. torquata proved only
D. BRYCE ON FIVE NEW SPECIES OF BDELLOID ROTIFERA. 89
moderately hardy. After a few days, most specimens would
feed freely under the unaccustomed light and would remain
quiet, but I have never known eggs to be laid under such
conditions.
By no means a common species, yet widely distributed ; I noted
it first in moss sent me in 1895 by Forstmeister L. Bilfinger,
of Stuttgart. I have since found it in moss from Epping Forest,
Essex ; Chagford, Devon ; Pass of Leny, Perthshire ; Black
Forest, Baden.
Dimensions. — Greatest length 410 fx, more frequently 320 to
350 fx. Corona 38 to 41 /x. Kami about 15 fx. Spurs 6 to 9 /x.
Habrotrocha spicula sp. nov. (PI. 9, fig. 1).
Specific Characters. — A single, short, blunt spine, sub-erect
upon dorsal median line of pre-anal segment. Corona small,
13-18 [x wide; pedicels adnate; upper lip high, rounded, un-
divided. Rami with four teeth each. Spurs, short cones, widely
separated.
A rather small species, chiefly noteworthy for the solitary
spine and its unusual position. No other Bdelloid yet known
has only a single spine or has spines only upon the pre-anal
segment as in this case. When the animal is in its most
retracted position, as one usually sees it lying inert among moss
debris, the spine stands out distinctly at the hinder end of the
body, and it is also well shown when the animal is feeding and
assumes the squatting position natural to many species. It is
easily overlooked when the animal is crawling about unless a
good side-view is presented. It springs from a thickened base,
and is rather blunt, short and slightly bent.
When seen from the front the very small corona is nearly
circular in outline, the trochal discs being separated by a shallow
furrow and the pedicels adnate. In dorsal view the high
rounded upper lip rises quite to the level of the trochal discs,
and its apex indeed is visible in ventral view. The margins of the
mouth have small angular lateral prominences, which are partly
90 D. BRYCE ON FIVE NEW SPECIES OF BDELLOID ROTIFERA.
visible even from the dorsal side and add to the apparent width
of the collar.
When extended the body is moderately stout and the longi-
tudinal skin-folds are well marked. In most cases it is colourless,
but examples of a faintly reddish colour have been seen. The
antenna is short, but rather stout. The rami are small, 14-15 tt
long.
The foot tapers rapidly and is very short. In the feeding
position it is usually hidden beneath the trunk. It seems un-
suited for crawling on a smooth surface such as glass, as the
animals have unusual difficulty in getting foothold. The first
joint has frequently a strong protuberance on its dorsal side.
The spurs are very small cones about 3 /x long separated by an
interspace about 6 /x wide.
The largest examples measured were about 200 jx long when
extended, but others were from 170 to 185 /x. My earliest speci-
mens were found in mosses collected for me on Cader Idris by
Mr. D. J. Scourfield in 1895. Others came from collections on
Mickle Fell and on Snowdon by the same friend. In 1898
I found it in moss from the top of Ben Ledi, in 1907 from the
top of Ben Vrackie, both in Perthshire ; and in 1906 from tree-
moss in the woods above Triberg in the Black Forest, Baden. It
has also been found repeatedly by Mr. James Murray in Scotland
and in many foreign habitats.
Distribution : cosmopolitan, mostly at high elevations.
Habitat : ground, rock or tree-mosses.
Habrotrocha ligula sp. nov. (PI. 9, fig. 2).
Specific Characters. — Moderately slender. Corona somewhat
wider than collar ; pedicels rather high, semi-adnate ; discs
separated by narrow sulcus. Upper lip rising very slightly and
displaying a small fleshy tooth, which near its apex tapers
suddenly to a point. Rami with four teeth each. Foot three-
jointed ; spurs small, tapering cones with interspace nearly equal
to their length.
D. BRYCE ON FIVE NEW SPECIES OF BDELLOID ROTIFERA. 91
A species of rather less than medium size which in its extended
position offers no obvious character for its recognition. The
rostrum is short and stout, and the dorsal surface has a distinct
almost ridge-like thickening of the hypodermis, best seen in
lateral view. Its movements are active when crawling about,
and when feeding it sways and bends almost incessantly in all
directions, the body being well extended and the upper foot
joints visible. The trochal discs are rather small and the
greatest width of the corona little exceeds that of the collar. The
pedicels are adnate to nearly half their height and are very
slightly divergent. At the dorsal end of the nexus between
them is a small fleshy ligule or tooth, which for the most part is
nearly cylindrical, but near the tip tapers rather suddenly to a
point. It is so inconspicuous that it can rarely be seen except
in direct dorsal view and when the animal keeps steady for a
brief interval. Even then the exact shape of the ligule is
difficult to determine, but I think that it differs somewhat from
the type of ligule possessed by any of the few Bdelloids in which
this peculiar ornament or organ has been seen. In Habrotrocha
eremita (Bryce), in which it was first noted, it is a simple, short,
peg-like tooth, very slender and tapering gradually, and, to judge
from the figures given by Murray, it appears to be of the same
character in Habrotrocha acornis Murray and Callidina lepida
Murray. In the present species the appearance is rather that
of a fleshy cylindrical pedestal, with a tapering point inset at
the end of the pedestal as if in a socket.
The upper lip rises in a low curve about as high as the base
of the ligule. The rami have four teeth, but one tooth on each
is much less prominent than the others. I have noticed that
the food pellets are rather small. Examples isolated produced
eggs of oval outline, hyaline, smooth-shelled, measuring 70 /x at
the longest by 43 //, at the shortest diameter.
I had this species first in 1894 from a roadside near Deal, and
in the following year from a wall in Bognor ; in both cases from
small button-like tufts of wTall-moss. I did not see it again until
92 D. BRYCE ON FIVE NEW SPECIES OF BDELLOID ROTIFERA.
some few weeks ago, when it was brought to me by Mr. G. K.
Dunstall, who had obtained it from moss collected near Leith
Hill, in Surrey. It is probably a more common species than
these three isolated records would indicate. It may be that it
has a partiality for small tufts of moss (which do not invite
examination), or perhaps its restlessness and the absence of any
very obvious peculiarity when marching about has led to its
being overlooked.
In view of Murray's opinion that the presence of a ligule in
Bdelloids is an unsafe specific character, as it often appears in
species where it is not normally present, it must be pointed out
that, while it may be presumed that the ligule in Habrotrocha
ligula is fairly constant, it is by no means impossible that
examples should occur in which it might be absent, and in that
case, if normal specimens were not available for comparison,
identification might well be difficult.
Dimensions. — Length about 320 fx. Corona 30 /x. Collar 25 /a.
Ramus 1 7 /x. Spurs 5 ll.
Callidina Bilfingeri sp. nov. (PI. 9, fig. 3).
Specific Characters. — Of medium size, and moderately stout,
posterior trunk having a series of knob-like prominences.
Trochal discs well separated, but corona not exceeding collar
width. Upper lip rather high and wide, with shallow central
depression. Rami with two teeth each. Dorsal antenna short,
about half the neck thickness. Foot three- jointed; first joint
laterally swollen, second very short, somewhat distended to form
sucker-like disc. Spurs very minute cones, with wide, slightly
convex interspace.
So far as I am aware, this rather well-marked species, of
moderately stout build and medium size, has been met with only
in ground-mosses. Typical specimens are easily recognised from
the series of knob-like prominences which ornament the sides of
the trunk segments and the dorsal surface of the rump segments.
D. BRYCE ON FIVE NEW SPECIES OF BDELLOID R0TIFER4. 93
The number of these "knobs" appears to be very inconstant,
as in sketches made by Forstmeister Bil finger, James Murray,
and myself it varies from eleven to five ; and I was informed
by the first-named correspondent that he had met with examples
without any knobs at all. In such cases the species can still be
determined with moderate certainty from the peculiar structure
of the second foot joint, and the minuteness and wide separation
of the spurs. When the full number of prominences are present
they are distributed thus : the third segment of the trunk (or
central portion of the body) has one at either side, close to its
anterior boundary ; the same segment and the fourth and the
sixth have each one at either side near their posterior boundaries;
while on the dorsal side of the fifth and sixth segments there are
three more, arranged in a triangle (two in front on the fifth
and one behind on the sixth segment, the latter on the median
line). The fifth segment is moderately swollen laterally. The
lateral knobs on the sixth segment (the anal) are more nearly
constant than the others. Those most frequently absent are
the anterior pair of the third segment.
The first foot joint has distinct lateral swellings, and is per-
haps swollen dorsally as well. The second joint is very short,
and slightly distended with thickened skin, forming a sucker-
like disc from the lower surface of which the three short, broad
toes are protrusible. The flange-like hinder margin of this
foot disc forms the slightly convex interspace between two very
minute spurs.
When creeping about the animal is seen to have a short and
stout rostrum. In the feeding position the body is somewhat
flattened, and the dorsal longitudinal skin-folds are obliterated.
The trochal discs are well separated, but the head is stout and
the corona does not exceed the collar width. The upper lip rises
rather widely and high, and has a shallow central depression.
The rami are 14 to 16 ^t long, and are widest above the middle.
The anterior outer margin of each is distinctly thickened, and
passes gradually into a delicate winglike expansion of the ramus.
94 D. BRYCE ON FIVE NEW SPECIES OF BDELLOID ROTIFERA.
As already stated, this species was first discovered by the
late Forstmeister L. Bilfinger in the vicinity of Stuttgart, and
notified to me in 1894. It was afterwards found by Mr. George
Western, probably near London, and in 1904 by James Murray,
near Fort Augustus. In 1906 I met with it in moss gathered
on the bank -of a roadside ditch near Triberg, in the Black
Forest. Quite recently numerous examples have been found in
moss collected by Mr. G. K. Dunstall near Leith Hill, Surrey.
Dimensions. — Length about 315 /a. Corona 38 /x. Collar 41 /a.
Spurs 1 to 2 /a (on inner edge).
i
Description of Plates 8 and 9.
Plate 8.
Fig. 1. Habrotrocha munda sp. nov., extended, dorsal view, x 350 ;
la, head and neck, corona displayed, in lateral view,
X 650 ; lb, the same, in ventral view, x 750 ; lc,
mouth, in front view (diagrammatic).
„ 2. Habrotrocha torquata sp. nov. In feeding position, corona
displayed, dorsal view, x 550 ; 2a, spurs, x 1600.
Plate 9.
Fig. 1. Habrotroclut spicula sp. nov. In feeding position, corona
displayed, ventral view, x 600 ; la, retracted position,
X 600 ; 16, foot extended, dorsal view, x 800 ; lc, ramus,
X1600.
,, 2. Habrotrocha ligula sp. nov. In feeding position, corona
displayed, dorsal view, x 480.
,, 3. Callidina Bilfingeri sp. nov. In feeding position, dorsal
view, x 350; 3a, ramus, x 1600.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 72, April 1913.
Joum.QM.C.
Ser. 2.Vol.XH,P1.8.
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95
NOTES.
A NEW LOW-POWER CONDENSER
By Edward M. Nelson, F.R.M.S.
{Read November 26th, 1912.)
The condensers which at present are supplied with microscopes
are only suitable for low powers ranging from | inch upwards.
With powers lower than these a difficulty arises, for it is not
possible to fill the field with the image of the source of light
focused upon the object, as it should be. Substage condensers
suitable for low powers are all too short in focus, consequently
the image of the source of light is far too small.
In these circumstances microscopists have been, and are,
accustomed to waive critical illumination and employ the most
uncritical of all illumination, viz. to focus the image of the
source of light upon the front lens of the objective ; this is
nothing more nor less than lantern illumination, which gives
a critical image of a diaphragm limiting the field, but of nothing
else ; all delicate lines and structures are coated with black
diffraction borders.
The obstacle in the way of using a long-focus condenser is that
there is not sufficient room to focus it.
Powell's No. 1 stand has a good deal of room, but not enough,
and other microscopes are simply nowhere. Now the way this
difficulty may be surmounted is to construct the condenser upon
the telephoto principle. This has now been done, and Messrs.
Baker will show you this evening a substage condenser they have
made from my design which has 4 inches of focal length and
requires only 1 inch of working distance. With this condenser
the image of the fiat of the flame bears the same relation to a
4-inch objective with the large field of a P. & L. No. 1 A eye-
piece, as the image with one of the ordinary universal condensers,
with the top off, does to a | inch ; and this is precisely what
was wanted.
Now let us understand exactly what this means. A 4-inch
objective has a focal length of 2| inches; with a No. 1 A
eyepiece the size of the object on the stage that is embraced
96 E. M. NELSON ON MICROSCOPE CONSTRUCTION
in a field of view is —$ inch, therefore it is necessary for the
condenser to focus upon the stage an image of the flat of the
flame ■—$ of an inch wide.
The condenser has a low aperture of N.A. 0*14, but large enough
for the objectives for which it is intended to be used.
NAVICULA RHOMBOIDES AND ALLIED FORMS.*
(Addendum.)
By Edward M. Nelson, F.R.M.S.
{Bead November 2M7i, 1912.)
With reference to the question, " What was the Amician Test?"
quite accidentally I recently came across a notice to the effect
that the test used by the Jurors at the International Exhibition
(London, 1862) was the Navicula ?'homboides under the name of
JV. affinis. This of course clears up all the difficulty. This
N. rhomboides would have been of the kind termed the
" English " rhomboides in my paper, and would have had 72 to
73 striae in 0*001 inch.
ON MICROSCOPE CONSTRUCTION AND THE SIDE
SCREW FINE ADJUSTMENT.
By Edward M. Nelson, F.R.M.S.
(Bead November 26th, 1912.)
There is one point which has been overlooked with respect to
the evolution of the microscope. It is thought that the modern
plan of placing the coarse adjustment slide and the body upon the
fine adjustment was the invention of Zentmayer (1876), and that
it first appeared in this country in the Ross-Zen t may er model.
This however is not the case, for Powell in 1841 invented this
plan, as well as that of the side pinion fine adjustment, now so
much in vogue.
In the frontispiece of Cooper's Microscopiccd Joumcd an illus-
tration of this model will be found, f Some years ago Mr. T.
* Journal Q.M.C., Ser. 2. vol. ii. p. 93.
f This was the first microscope Powell introduced after Lealand had
joined the firm (vide Journal B.M.S., 1900, p. 287, fig. 78).
AND THE SIDE SCREW FINE ADJUSTMENT. 97
Powell kindly showed me one of these microscopes, but it had
escaped my memory. The coarse adjustment was by rack and
pinion ; this was not attached to the limb by a slide, but by a
kind of cradle. This cradle was pressed down by a spring on
to a horizontal cone, which was moved by a horizontal fine-
adjustment screw, which had a milled head on each side of the
limb.
The importance of this model should be recognised by every one
who uses a microscope, for not only was it the first microscope
to have a side screw, but also it was the first instrument in
which we find the limb attached to the foot on two upright
pillars. This double support to the joint (now almost universally
used) was the invention of George Jackson (President R.M.S.
1852-3). Before this all microscopes that were capable of being
inclined were attached to the foot by a single upright post and a
compass joint.* Powell attached the two pillars to a flat tripod
base by a swivel so that the base could be placed in such a
position as to give the greatest amount of stability however
much the body might be inclined (some makers in copying this
arrangement graduated this arc of rotation !).
Ross copied this kind of joint in the model he brought out in
1843, but substituted two parallel flat plates for the two pillars ;
but Messrs. Smith and Beck adopted the two-pillar form in their
1846 model.
This microscope of Powell's had a Turrell stage, a micrometer
stage, an achromatic condenser, Nicol polarising and analysing
prisms ; so it was in its day an instrument of a very advanced
type. In 1843 Powell & Lealand discarded the two pillars for
the gipsy tripod, which is the best form of foot ever designed.f
Coming now to modern times, horizontal fine adjustments may
be placed in two groups, viz. (a) those with continuous motion
and (b) those without. The drawback which those of the first
kind possess is that the user does not know whether he is
focusing up or down ; and the drawback which all the second
kind, excepting the Berger, have is that of damage and injury to
the delicate moving parts when they butt up against a stop.
The Berger avoids all risk of damage from this source by causing
* Some ancient non-achromatic microscopes had ball and socket joints,
but those early forms are not now under discussion,
t For fig. see Journal R.M.S., 1900, p. 289, fig. 79
Journ. Q. M. C, Series II.— No. 72 7
98
E. M. NELSON ON MICROSCOPE CONSTRUCTION.
an idle nut to butt against a stop ; if this nut receives damage or-
strain to its thread it is of no importance. The first kind adopt
a continuous motion in order to secure immunity from this
danger, and put up with the great disadvantage of having a fine
adjustment which does not follow the direction of the movement
of the milled head.
The following simple device has been designed to effectually
prevent any damage taking place. To the right hand side of the
limb, where the micrometer drum-head is placed, a short piece of
tube, threaded on the outside, is fixed, and through it the fine
adjustment pinion passes just like the cannon pinion in a clock.
Fig. 1.
Fig. 2.
An idle nut works on this screw in a slot inside the micrometer
drum. It is then arranged that this nut will permit ten rotations
of the fine-adjustment pinion to be made, and then stop further
motion by butting either against the side of the limb or against
the end of the inside of the micrometer drum. Figs. 1 and 2 will
make this simple device clear without further explanation.
NOTE ON PLEUROSIGMA ANGULATUM.
By Edward M. Nelson, F.R.M.S.
{Read January 28th, 1913.)
About the end of the eighties I took a photomicrograph of a
specimen of Pleurosigma angulation, which had been broken in
a very remarkable manner so that it was possible to demon-
E. M. NELSON ON V LEU RO SIGMA AStiULATUM. 99
strate the existence of two membranes. At one part the upper
membrane had been torn away leaving the lower membrane,
at another the lower membrane had gone while the upper was
left, the rest of the valve having both membranes in position.
These three photomicrographs of the upper, lower and both
membranes were exhibited to the Club. No other specimen I
have seen has been so fortunately fractured as to demonstrate
both membranes so clearly as this one.
The network in one membrane differs slightly from that of
the other, so that after a little practice one is able to state
whether the membrane under observation is an upper or lower
membrane. The upper membrane in P. strigosum resembles
the diamond panes of a leaded light, while the lower is like
wire netting, fig. 3. In P. balticum and allied forms the upper
memb^ine has slit-like apertures in longitudinal rows, while
III
O-go
Fig. 3. Fig. 4.
the lower membrane has circular apertures, fig. 4, where the
circular apertures in the lower membrane are seen through
the intercostal silex of the upper membrane and in a line with
the bars between the slits.
Now at that time it was thought, and probably it is still
the received opinion, that the lower membrane " eye-spotted "
the upper membrane ; by which is meant that the apertures
in the lower membrane are directly below those in the upper
membrane — much in the same way as in Coscinodiscus the eye-
spot is directly below the perforated cap at the top of the cell.
Recently, however, study on P. angidatum with a Leitz apo-
chromat, y1^ inch of 1*40 N.A., has caused me to change my
opinion, for the apertures in the lower membrane can be un-
mistakably seen below the intercostals of the upper membrane,
and this is true not only of P. angidatum, but also of all allied
forms that have been examined.
No mention has been made of Mr. T. F. Smith's observation.
100 E. M. NELSON ON PLEUROSIGMA ANGULATUM.
on the structure of the genus Pleurosigma, because this note,
not being an exposition of the structure of this genus, deals
merely with the single fact of my altered opinion with regard
to the apertures in the lower membrane not " eye-spotting "
those in the upper.
The genus Pleurosigma has been seventy years before the
microscopical world, not laid aside, but worked at continuously
by the most skilful microscopists, yet all the problems con-
nected with their structure have not been solved. It is only
by recording from time to time a little bit here and a little
bit there, and by putting these little bits together, that complete
and accurate knowledge of this difficult subject will be attained.
ACTINOCYCLUS RALFSII AND A COLOURED COMA.
By E. M. Nelson, F.R.M.S.
{Read January 28th, 1913.)
The following account of a microscopical phenomenon, never
previously observed, may be of interest.
When working on a mixed diatom gathering, dry and un-
covered, with a Powell & Lealand | inch and a lieberkuhn, there
appeared round an Actinocyclus Ralfsii a wide border of brilliant
orange, green and blue light. The inside of the valve was
uppermost and the bottom of the cup was in focus, so that the
surrounding mist was caused by the out-of -focus edge, which, of
course, was at a higher level. Any one seeing this coloured mist
would have exclaimed what a badly corrected objective ! but if
they had looked at the other diatoms in the field, they would
have seen that the out-of -focus coma was white ! The colour,
then, must be a function of the Actinocyclus. Another objective
with a lieberkuhn, viz. a Powell & Lealand T4^ inch, was tried on
the same diatom ; the border was now red, the green and blue
having gone ! A third objective, viz. a Wenham | inch with
lieberkuhn (really a T4<y inch), and the image seen had no colour !
Here, then, we have an example of an object affecting different
objectives differently. Would some of our " brass and glass "
experts kindly take this matter up ?
Joara. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 72, April 1913.
101
NOTICES OF BOOKS.
Problems of Life and Reproduction. By Marcus Hartog,
M.A., D.Sc., F.L.S. 8 x 5J in. ; xx -f 362 pages ; one
plate, 41 figures in the text, and three diagrams. London :
John Murray, 1912. Price 7s. 6d. net.
In taking up this book one cannot avoid a feeling of regret
that the author was unable to carry out his original intention of
writing a general treatise on Reproduction suited to the layman
interested in biological questions. By his researches the author
would have been well fitted for such a task. As it is, the book
consists of a series of papers on debatable subjects in Biology
gathered from various scientific journals and reviews, and ranging
in date from 1892 to 1910. They have been revised in part in
the light of more recent research, and brought up to date.
There is much to interest the microscopist, and to one who is
not already acquainted with them in their original form they may
be recommended. The earlier papers deal with the problems
of reproduction as presented in the Protista — conjugation and
rejuvenescence and the beginnings of sexual reproduction or
syngamy. The paper on Fertilisation contains a large number
of interesting facts gathered together ; here the author puts
forward the idea that it is the linin and not the chromatin
(which only serves a purely mechanical function) which is the
real transmitter of inherited properties. This idea is more
fully developed in Chapter 1Y. on " Mitokinetism " — a new
force which the author brings to our aid in explaining the
mechanics of the mitotic process of nuclear division. Other
chapters deal with heredity and the inheritance of acquired
characters and Mechanism and Life.
There are a number of illustrations and a coloured plate; a
full index is provided.
102 NOTICES OF BOOKS.
The Beginner's Guide to the Microscope, with a section on
mounting slides. By Charles E. Heath, F.R.M.S. 1\ x
5 in. 119 pages, 45 figures in text. London: Percival
Marshall & Co., 1912. Price Is. net.
In this elementary guide to the study of Microscopy the author-
has treated the subject from a practical point of view, leaving
theoretical matters to the larger books on the subject. With this
little book at hand the beginner cannot fail to gain a useful
knowledge of the instrument, its care and its application. The
methods of illumination, including the dark-ground method, are
fully dealt with. As the author says, the book is intended " to
enable an ordinary man in an ordinary way to interest himself
and his friends by giving sufficient instruction to make him capable
of seeing and showing some of the hidden wonders " revealed by
the microscope.
103
PROCEEDINGS \fy
OF THE
QUEKETT MICROSCOPICAL CLUB.
At the meeting of the Club held on October 22nd, 1912, the
President, Prof. A. Dendy, D.Sc., F.R.S., in the chair, the
minutes of the meeting held on June 25th, 1912, were read and
confirmed.
Messrs. William Elliott and Leabury Edwardes were balloted
for and duly elected members of the Club.
Seventy-three members and live visitors were present.
Thirteen proposals for membership were read by the Hon.
•Secretary.
The list of donations to the Club was read and the thanks of
the members were voted to the donors.
A letter addressed to the President by Mr. Charles Peveril
was read, intimating that the late Mr. J. M. Allen, F.R.M.S.,
had bequeathed to the Club his microscopes and apparatus
belonging thereto. This legacy was accepted by the Committee ;
it consists of two microscopes and some small accessories.
The Librarian announced that he had received a copy of
L. L. Clark's " Objects for the Microscope " to replace a copy
missing from the library, also that Prof. Minchin's " Intro-
duction to the Study of the Protozoa " had been presented by
the author.
A communication from Mr. J. Rheinberg, F.R.M.S., " On
Resolutions Obtained with Dark-ground Illumination and their
Relation to the Abbe Theory," in the absence of the author, was
taken as read.
A very interesting paper, " The Foraminifera in their Role
as World-Builders," by Messrs. Earland and Heron- Allen, was
read by Mr. Earland, and illustrated by a large number of
.pictures of the various forms described, which were shown upon
104 PROCEEDINGS OF THE
a screen by Mr. Ogilvy by means of the Epidiascope, and by
specimens of the deposits placed upon the table.
The President said it was hardly necessary to ask them to-
give a hearty vote of thanks to Mr. Earland for reading them
such an interesting paper. A vote of thanks was carried by
acclamation.
Through the kindness of Messrs. Leitz's London representative,
Mr. Ogilvy, the lecture was very efficiently illustrated by the
use of the Leitz universal projection apparatus, which projected
on the screen ordinary lantern -slides, plates and illustrations
from books, etc., single photographs, microscopic sections at
varying magnifications, rock hand-specimens and fossils. The
capabilities of the apparatus, which employs an automatic L-arc,.
taking 30 amp. at about 60 volts, were further demonstrated by
Mr. Ogilvy and his assistants after the meeting. The approxi-
mate candle-power produced is about 10,000. Micro-projection
may be accomplished in the usual horizontal position, and, for
hanging drop slides or other living preparations, a vertical
position is also possible. Besides the projection of lantern-slides
of any size up to 12 cm. square (4|in.), for which a novel and
exceedingly efficient holder is provided, it is also possible to
project larger transparencies up to 20 cm. square (8 in.), or such
preparations as brain sections, etc.
The President said they were all very much indebted to Mr.
Ogilvy for what he had shown them ; he had himself been
greatly interested to see how perfectly the Epidiascope was
adapted for showing drawings, lantern-slides and microscopic
specimens on the screen in a manner which he had not previously
been aware of.
The Hon. Secretary regretted to have to announce the recent
death of Dr. M. C. Cooke, M.A., LL.D., A.L.S., one of t he-
original founders of the Club, and President 1882-3.
At the meeting of the Club held on November 26th, 1912, the
President, Prof. A. Dendy, D.Sc, F.R.S., in the chair, the
minutes of the meeting held on October 22nd were read and
confirmed.
Messrs. E. Pitt, G. C. Bellamy, T. Tonkin, H. Pulford,.
E. H. Bassett, L. C. Hayward, William Hill, D. A. Mardonr
QUEKETT MICROSCOPICAL CLUB. 105
P. E. Dollin, F. Whitteron, J. M. Coon, E. W. H. Row and
W. Hardinan were balloted for and duly elected members of
the Club.
The list of donations to the Club was read, and the thanks of
the members were voted to the donors.
The President said that members would be very glad to hear
that the announcement made at their last meeting, of Dr. Cooke's
death, was incorrect. They had it apparently on the best
authority, and the scientific Press generally had been similarly
misinformed. lie was sure that all members would hope that
Dr. Cooke would long remain a member of the Club.
The President asked members to extend a hearty welcome to
a visitor, Dr. E. P. Hodges. Dr. Hodges was State Medical
Supervisor for Indiana, U.S.A., had been for many years a
Fellow of the Royal Microscopical Society, and took the greatest
interest in microscopy generally.
Mr. C. Lees dirties, for Messrs. Baker, exhibited a new
one-sixteenth oil-immersion objective of N.A. 1*32. It was
made of a stable glass — one that would stand any climate. Its
qualities were appreciated by members, who admired the
excellent definition it gave (with a x 7 ocular) on a fine pre-
paration of Trypanosoma gambiense.
The President made some remarks relating to a new species of
Holothurian. He said he had no formal paper to read, but the
subject had been before the Club a few months ago {Journ.
Q.M.C., Ser. 2, Vol. XI. p. 536), when an Australian visitor,
Mr. F. Whitteron, of Geelong, had brought for distribution a
number of specimens of a species of Holothurian which had an
interesting history. They had been collected in Corio Bay, Port
Phillip. Continental experts had identified the species as Trocho-
dota dunedinensis (Parker). That identification, however, proved
to be incorrect, and, as specimens had been distributed at their
June meeting, he thought it proper to bring the matter before
the notice of the Club. On examining the material he had then
taken, he found that all the calcareous wheels had been dis-
solved, possibly by the medium in which they were preserved
being, or becoming, slightly acid. Fortunately, this failure was
not of importance, as, in a reprint he had received from the
Proceedings of the Royal Society of Victoria, Mr. E. C. Joshua,
of Melbourne, discussed the species found at Geelong, and
106 PROCEEDINGS OF THE
definitely showed that it was not identical with the New Zealand
form. He calls the Geelong species Taeniogyrus Allani. The
President referred to the varying nomenclature of these species.
He considered all the forms closely related, and preferred the
generic name Chiridota, applied by Parker to the New Zealand
form. The differences between the New Zealand and Geelong
species were then considered. The structure of the wheel spicule
had been worked out by Mr. Joshua, and was described in his
paper. The President had worked out the N.Z. form some years
ago, and described and sketched on the blackboard the various
stages observed. The spicule has a broad margin, corresponding
to the rim of the wheel. Then there are six spokes radiating
from the centre, and in some species there is a small hole in the
middle. Specimens of C. dunedinensis exhibit a uniform minute
toothing all round the margin, which is inturned. The other
side of the wheel has a different appearance. The six spokes
show as before ; but the toothed edge is not seen at the top
focus. Further, fresh detail is exhibited in the form of a
six-rayed cross, which stands above the level of the spokes. A
diagram of a vertical section was given. The President said it
was a very curious and wonderful structure, and the development
was of extreme interest. Commencing with the six-rayed cross,
a thickening appears at the end of each ray, and on one surface
only. This was the earliest stage observed. As the thickenings
grow, they exert pressure on each other, and presently each
spoke bifurcates at the extremity. The bifurcated ends begin
to grow outward, and presently meet, and, fusing, form the rim
of the wheel. The rim turns in, and is denticulated all round
the margin. The spicule is, of course, useful as a skeletal
structure ; but it is not at all apparent why such a remarkable
and elaborate form should be required. The chief differences in
C Allani, as compared with C. dunedinensis, are : The margin,
instead of rounding off, remains hexagonal. The face showing
the six-rayed cross is much the same, excepting that it also is
hexagonal ; but the toothed rim is not uniform, but follows
a curve with little bays opposite the angles of the hexagon, and
the toothing is pronounced in parts, but is absent from the bays
or notches. It is very difficult to account in any way for such
minute differences as those noted. The new form, which he
would prefer to call Chiridota Allani, was first found by Mr.
QUEKETT MICROSCOPICAL CLUB. 107
J. M. Allan, near Geelong, and subsequently by Mr. E. C.
Joshua.
Replying to a question, the President said that formalin was
very unsafe to use in such cases, as it frequently becomes acid
after a short time.
Mr. J. Burton said he took some of the material brought by
Mr. Whitteron, and, after some trouble, had found some
wheels in the skin. They looked as though acid had been
previously applied. The wheels showed a tendency to break
down into anchors, reminding one of the well-known Synapta
spicules. The anchor form, as the President had said, was an
early stage in the development of the wheel. The wheels, under
a, binocular, proved to be basin-shaped. There was a second
kind of spicule, something like a drawer- handle in shape, and a
third shape, found only in the tentacles, where it was very
numerous, constituting, perhaps, 50 per cent, of their bulk.
The thanks of the meeting were unanimously voted to the
President for his communication.
Several notes from Mr. E. M. Nelson were read to the meeting
by the Hon. Secretary, as under :
1. "On Microscopic Construction and the Side-Screw Fine
Adjustment," in which he traced the history of this form from
1841 to the present time, with some suggestions of his own for
further improvement.
2. On the Navicula used as a test by the Jurors of the 1862
Exhibition, which he thought was the " English " rhomboides
under the name of Xavicula affinis.
3. " On a New Low-power Condenser :' for use with objectives
as low as 4 in., the ordinary condenser not filling the field with
light when low powers were used.
The way this difficulty may be surmounted is to construct
the condenser upon the telephoto principle. This has now been
done, and Messrs. Baker exhibited to the meeting a substage
condenser, made from Mr. Nelson's design, which has 4 in. of
focal length, and requires only 1 in. of working distance. With
this condenser the image of the flat of the flame bears the same
relation to a 4-in. objective with the large field of a P. and L.
No. 1, A eyepiece, as the image with one of the ordinary uni-
versal condensers with the top off does to a twro-thirds ; and
this is precisely what was wanted.
108 PROCEEDINGS OF THE
The thanks of the Club were voted to Mr. Nelson for his
communications.
At the meeting of the Club held on January 28th the
President, Prof. A. Dendy, D.Sc, F.R.S., in the chair, the
minutes of the meeting held on November 26th, 1912, were
read and confirmed.
Messrs. Hilary Mavor, Robert Spry, E. J. Sheppard, F.R.M.S.,.
A. C. Coles, M.D., D.Sc., A. M. Allison and H. W. Freeland
were balloted for and duly elected members of the Club.
The list of donations to the Club was read and the thanks
of the members voted to the donors.
Mr. Watson Baker, for Messrs. Watson & Sons, Ltd., ex-
hibited and described a new model microscope which had a
specially long horizontal travel, If in., to the mechanical stage,
both movements working on the same axis. The fine adjustment
is a vertical lever actuated by the now customary side-screw,
and permitting the worker to always know whether the body
is ascending or descending. It has a specially long range of coarse
adjustment. The most important novelty on the stand was a
new objective changer, made on the principle of a 3-jaw chuck ;
less than a quarter-turn of a collar is all that is necessary to
engage or release an objective, and it does not increase the tube
length. An auxiliary stage was also shown. This, fitted to the
usual stage, will give nearly four inches of horizontal travel,
and should be found very useful in working with large pre-
parations.
Mr. A. A. C. Eliot Merlin, F.R.M.S., sent a photomicrograph
taken at x 320 of Coscinodiscus heliozoides, showing extended
" pseudopodia," from a preparation by Mr. J. D. Siddall.
The fine radiating " pseudopodia " can be well seen when the
print is examined in a good light with a Verant or other suitable
hand magnifier. The photograph gives the impression that the
radiating filaments are real appendages of the organism, and
the general appearance of these reminds one strongly of the
pseudopodia of Discorbina globidaris as figured in Carpenter
(1901 edition), page 798.
The photograph as a whole strikes one as more curious than
beautiful. It will, however, be noticed with a lens that several
of the radiating filaments are very fine and in exact focus.
QUEKETT MICROSCOPICAL CLUB. 109
The best focal plane for the " pseudopodia " does not coincide
■with that for the diatom itself, and this, together with the
prolonged exposure necessary to bring out the faintly illuminated
filaments, causes the valve to be much over-exposed, making
the diatom appear as a mare blurred, globular white patch in
the print.
The President gave a resume of a communication of some
length by Mr. W. M. Bale, F.H.M.S., of Victoria, Australia,
entitled " Notes on Some of the Discoid Diatoms." This paper
was a survey of some of the principal characters which have
been utilised in the discrimination of species in three or four
of the best-known genera of discoid diatoms. Some of the
conclusions arrived at as to the inadequacy of many of these
distinctions have been reached by previous observers, more
especially in the genus Coscinodiscus ; but it was thought that
in such cases the special instances now brought forward might
be serviceable in reinforcing those conclusions. In other cases,
particularly in the genus Actinoptychus, the author's observa-
tions tended to prove that characters accepted as specific even
by recent authors were demonstrably unreliable. The genera
dealt with included Coscinodiscus, Actinocyclus, Asteromphalus
and Actinoptychus.
The thanks of the meeting were unanimously voted to the
President for communicating this important paper.
A paper on " British Freshwater Bhabdocoelida (Planarians),
a Group of Turbellaria," by H. Whitehead, B.Sc, in the absence
of the author was read by Mr. J. Wilson.
After some discussion, in which Messrs. Scourfield and Ham-
mond took part, the President said that the Bhabdocoelids were
very low down in the scale, some of them ranking among the
lowest of multicellular organisms. Most of his own work in
Australasia had been done on land forms, but there were, pos-
sibly, water forms as well. There were in Australia an enormous
number of land Planarians which lived under stones, rocks, logs,
etc., and only came out at night. Some were very large, reach-
ing a length of one foot. They are locally incorrectly termed
" land-leeches." Many are brightly coloured in stripes, spots,
and patches of brilliant blue, red, yellow, orange, and sometimes
iridescent. These colourations were very useful in assisting
naturalists to identify species. He had described some forty new
110 PROCEEDINGS OF THE
species from Australia and New Zealand, and was very glad to
see that the study of the group was being taken up in this-
country.
The Hon. Secretary read a " Note on Pleurosigma angalaturu"
by Mr. E. M. Nelson, F.R.M.S., also a note on a coloured coma
observed in examining A. Ralfsii, by the same author.
Mr. C. F. Rousselet, F.R.M.S., read a paper on "The Rotifera
of Devils Lake, and description of a new Brachionus."
At the meeting of the Club held on February 25th, the Presi-
dent, Prof. A. Dend}r, D.Sc, F.R.S., in the chair, the minuter
of the meeting held on January 28th were read and confirmed.
There were present ninety -three members and fourteen visitors.
Messrs. H. T. Laurence, F. W. Mills, J. W. Durrad, W. Oatley,
E. A. Anstey, C. D. Hutchin, A. Booker, F. W. Parrott, J. J.
Armitage, N. Burns, J. Snell, A. 0. Trotman, R. A. Taylor,
J. Bancroft, J. E. Barnard, R. Hall, V. Tyas and Dr. J. C.
Kaufmann were balloted for and duly elected members of the
Club.
The list of donations to the Club was read and the thanks of
the members voted to the donors.
The President having appointed Messrs. Fuller and Watson -
Baker, jun., as Scrutineers, the ballot for Officers and Council
was proceeded with.
The Hon. Secretary (Mr. \V. B. Stokes) read the Committee's
forty-seventh Annual Report. It was considered that the past
year was one of marked progress. Forty new members had been
elected; five members had died and fifteen had resigned during
the past year. The total membership on December 31st, 1912,
was 406.
The Hon. Treasurer (Mr. F. J. Perks) presented the Annual
Statement of Accounts and the Balance-sheet for 1912, which
had been duly audited and found correct.
The Report and Balance-sheet were received and adopted, on
the motion of Mr. Morland, seconded by Mr. Gaff.
The President, having asked Prof. E. A. Minchin to take the
chair, delivered his Annual Address, taking as his subject " By-
products of Organic Evolution."
Prof. Minchin said he was sure all present would agree that
QUEKETT MICROSCOPICAL CLUB. Ill
they had listened to a very fascinating address from one who
was the foremost living authority in Europe on sponge spicules.
The Club was very fortunate in having the subject dealt with by
him. The objects were quite well known to all microscopists, and
he believed he was right in saying that all the different forms of
spicules described could be obtained from sponges found on our
own coasts. He had great pleasure in moving a hearty vote of
thanks to their President for his address, and in asking him to
allow it to be published in the Journal.
The motion having been put to the meeting, was carried by
acclamation.
The President, in acceding to this request, thanked the mem-
bers for the way they had received the address, but said he had
thought himself that Prof. Minchin was the greatest authority
they had on these microscopic objects.
A vote of thanks to the Auditors and Scrutineers, having been
moved by Mr. W. R. Traviss and seconded by Mr. A. M. Jones,
was put to the meeting and carried unanimously.
Mr. Bremner then moved that their best thanks be given
to the officers of the Club for their services during the year.
They had given them a very valuable amount of time with a
most excellent result. Mr. Stokes had referred to the work
done by their Librarian, which must have occupied hundreds
of hours, and as for Mr. Stokes himself his unfailing courtesy
and his capacity for hard work were deserving of their highest
appreciation.
Mr. A. D. Michael said he always felt very strongly that
the great success which attended the scientific societies of London
was mainly due to the work done by their officers. He had
much pleasure in seconding the vote of thanks to those who had
so ably conducted the business of the Club during the year.
Mr. W. B. Stokes said that as this was the last occasion on
which he would be able to speak as an officer of the Club he
would reply for his colleagues ; he thanked the members for
the vote they had just carried. He felt he was leaving the
Secretaryship in better hands than his own ; but was very glad
that he was leaving it not when the Club was at the bottom
of a curve of prosperity, but very nearly at the top. He thanked
the officers for the ready assistance which they had always given
him, and which had rendered his duty a pleasant one, and he
112 PROCEEDINGS OF THE QUEKETT MICROSCOPICAL CLUB.
desired also to thank the members for the kind way in which
they had supported him during his term of office as their
Secretary.
The President announced the result of the ballot for Officers
and Committee to be as follows : —
President
Vice-Presidents
Treasurer .
Secretary
Assistant Secretary
Foreign Secretary
Reporter ....
Librarian .
Curator ....
Editor ....
Vice four senior
Members retired.
Vice James Burton
{apptd. Secretary.)
Prof. Arthur Dendy, D.Sc, F.R.S.,
F.L.S.
C. F. Rousselet, F.R.M.S.
E. J. Spitta, L.R.C.P., M.R.C.S.,F.R.A.S.
D. J. Scourfield, F.Z.S., F.R.M.S.
.Prof. E. A. Minchin, M.A., F.R.S.
Frederick J. Perks.
James Burton.
J. H. Pledge, F.R.M.S/
C. F. Rousselet, F.R.M.S.
R. T. Lewis, F.R.M.S.
S. C. Akehurst.
C. J. Sidwell, F.R.M.S.
A. W. Sheppard, F.Z.S., F.R.M.S.
R. Paulson, F.R.M.S.
J. Grundy.
M. Blood, F.C.S., F.R.M.S.
.0. D. Soar, F.L.S., F.R.M.S.
R. Inwards, F.R.A.S.
11
o
FORTY-SEVENTH ANNUAL REPORT,
Reviewing the work of the Club during the year 1912 shows
that it has been a period in which its high value to the user
of the microscope has been again demonstrated. Not only has
the Club maintained the interest of its meetings, but it has
exhibited a revival of interest in matters connected with the
instrument itself. There has been a very good attendance at
conversational meetings, and the favour shown to the excursions
during a season having a record rainfall is well worthy of note.
The number of new members added during the twelve months
is forty, 50 per cent, advance on that of 1911, and this number
would have been even greater if an ordinary meeting in Decem-
ber had been possible. The Club has lost five members by
death, and resignations have accounted for fifteen ; this leaves
a net gain of twenty members. The total membership on
December 31st was 406.
The following communications have been made during the
year : —
Jan. James Burton. Notes on Algae collected in 1911.
Feb. Prof. E. A. Minchin, F..R.S. Some Speculations with
regard to the Simplest Forms of Living Beings and
the Origin of Life.
March. H. Sidebottom. Lagenae of the South-west Pacific.
„ C. F. Rousselet, F.R.M.S. On New Species of Rotifera.
,, D. Bryce. On New Species of Callidina.
„ A. E. Conrady, F.R.A.S. On Resolving Powers ob-
tainable with Dark-Ground Illumination.
„ A. A. C. Eliot Merlin, F.R.M.S. On the Capped
Secondaries of Navicula Smithii.
April. John Stevens, F.R.M.S. On Notommata glgantea
(Glascott).
„ Duncan J. Reid. Illumination in Critical Work.
May. E. M. Nelson, F.R.M.S. On the sculled fseudopodia
of certain Diatoms.
Journ. Q. M. C, Series II.— No. 72. 8
114 FORTY-SEVENTH ANNUAL REPORT.
May. R. T. Lewis, F.R.M.S. Notes on Solpuga.
,, A. E. Oonrady, F.R.A.S. Some Experiments on Alter-
native Microscopical Theories.
June. W. B. Stokes. Resolutions obtained with Dark-
Ground Illumination and their Relation to the
Spectrum Theory.
„ R. W. H. Row. On a Saw-fly.
Oct. Julius Rheinberg, F.R.M.S. On Resolutions obtained
with Dark-Ground Illumination and their Relation
to the Abbe Theory.
A. Earland, F.R.M.S., and E. Heron-Allen, F.L.S.
Foraminifera as World Builders.
Nov. Prof. Arthur Dendy, F.R.S. On a New Species of
Holothurian.
E. M. Nelson, F.R.M.S. On Microscope Construction.
On Namcula rhomboides.
55
M 55 5? >5
On a New Low-Power Con-
55 55 5) 55
denser.
The following exhibits were made : —
Jan. E. M. Nelson, F.R.M.S. Photomicrographs.
,, A. Earland, F.R.M.S. Photomicrographs of Recent
Foraminifera.
„ W. Watson & Sons, Ltd. Microscope Tray.
,, Charles Baker. Nelson's Dark-Ground Illuminator.
March. T. W. Butcher, F.R.M.S. Photomicrographs of Nam-
cula Smithii.
„ Charles Baker. Nelson's Oil Immersion Dark-Ground
Illuminator.
,, Charles Baker. Nelson's Improved Chromatic Con-
denser.
„ Charles Baker. Nelson's Improved Rousselet Com-
pressor.
April. C. D. Soar, F.R.M.S. Drawings of Water-Mites.
„ A. W. Stokes. Electric Lamps for the Microscope.
„ C. F. Rousselet, F.R.M.S. Diatoms with "Pseudo-
podia."
„ Charles Baker. A New l|-in. Objective of N.A, 0'18.
Oct. E. Leitz. The Epidiascope.
FORTY-SEVENTH ANNUAL REPORT. 115
Nov. Charles Baker. A New l/16th-inch Oil Immersion
Objective.
,, Charles Baker. Nelson's New Low-Power Condenser.
Your Committee wish to thank the authors and exhibitors
for these interesting communications and exhibits. It will be
seen that there has been no falling-off in either the quality or
quantity of papers submitted to the Club.
There were eleven excursions during the season, and all were
well attended, except on one occasion when the weather was
very bad ; the record number of fifty-three members met to visit
the Royal Botanic Gardens. The total attendances for all ex-
cursions was 235, which is also a record for any one year, and the
average of 21*4 per excursion has only been exceeded once before.
The collecting, though not including anything new, was always
satisfactory.
The thanks of the Club are due to the Secretary of the Royal
Botanic Gardens and to the Metropolitan Water Board for
permission to visit their enclosures ; also to the Port of London
Authority and Mr. Carlyle, who so kindly entertained the
members at tea after their visit to the Surrey Commercial Docks.
Later in the year a party of members gave an exhibition of
Pond Life at the Dock Club and Institute, on which occasion
Messrs. Soar, Offord and Wilson gave short lectures with lantern
illustrations.
The Hon. Librarian and his assistant have expended a con-
siderable amount of time and labour upon the classification and
arrangement of the Club's books, and great progress has been
made with the preparation of the new catalogue. The amount
allotted to the cost of binding has been exceeded by £5, and
repairs and cases for loose parts have cost about <£11. The
question of the elimination of periodicals containing nothing of
particular interest to microscopists is before your Committee ;
the limitation of space for housing the Club's books being a
difficulty that it has to meet. The Library has been used in
1912 as much as in previous years, but the cost of housing
relatively to the use that is made of the books presents quite
a serious problem for consideration by your Committee.
During the year under review the following volumes have been
added : —
116 FORTY-SEVENTH ANNUAL REPORT.
LIST OF BOOKS PURCHASED SINCE APRIL 1912.
SlJSSWASSERFAUNA DEUTSCHLANDS :
Part II. Copepoda, Ostracoda, Malacostraca.
,, XIV. Rotatoria and Gastrotricha.
Science of the Sea. Edited by G. H. Fowler. Issued by the
Challenger Society.
Huyghen's Treatise on Light. Translated by Prof. Silvanus P.
Thompson.
Also fifty copies of Henry Sidebottcm's paper, " Lagenae of
the South-West Pacific Ocean," reprinted from the Q. M. C.
Journal, April 1912, Vol. XI. These copies may be purchased
at 2s. Qd. each.
LIST OF BOOKS PRESENTED SINCE APRIL 1912.
Presented by the Author, E. Penard :
Notes sur quelques Sarcodines. Part I.
Presented by ft. T. Lewis :
Objects for the Microscope. 2nd Ed. . . L. Lane Clark.
Presented by Julius Rheinberg :
Spectrum Method of Colour Photography.
Presented by the Author, Prof. E. A. Minchin :
Introduction to Study of Protozoa.
Presented by James Motham :
List of the Fossil Radiolaria from Barbados. A. Earland.
Figured in Ehrenberg's Fortsetzung.
Radiolaria ....... A. Earland.
Reprinted from the Q. M. C. Journal, April 1900.
Presented by Mrs. D. Wesche :
Phylogeny of the Nemocera . . . W. Wesche.
With notes on the leg bristles, hairs and certain mouth glands
of Diptera.
FORTY-SEVENTH ANNUAL REPORT. 117
Presented by the Author, E. Penard :
Notes sur quelques Sarcodines. Part II., 1906.
Presented by the Author, Dr. J. B. De-Toni :
Sylloge Algarum :
Vol. T. Sections I. and II. Chlorophyceae.
,, II. Bacillarieae.
,, III. Fucoideae.
,, IV. Sections I., II., III., IV., Florideae.
,, V. Myxoph}-ceae.
Presented by the Author, C. E. Heath :
Beginners' Guide to the Microscope.
During the year ending December 1912 the Library has
received the following publications :
Quarterly Journal of Microscopical Science.
Victorian Naturalist.
Mikrokosmos.
Royal Microscopical Society.
British Association.
Royal Institution.
Geologists'1 A ssociation.
Manchester Literary and Philosophical Society.
Hertfordshire Natural History Society.
Bristol Naturalists' Society.
Birmingham Natural History and Philosophical Society.
Botanical Society of Edinburgh.
Glasgow Naturalists Society.
Croydon Natural History Society.
Indian Museum (Calcutta).
Royal Society of New South Wales.
American Microscopical Society.
Sin ithsonian Instit ution.
Academy of Natural Science, Philadelphia.
Missouri Botanic Garden.
Philippine Journal of Science.
Bergen Museum.
Lloyd Library, Cincinnati.
118 FORTY-SEVENTH ANNUAL REPORT.
U.S. National Herbarium.
Royal Society. Series B.
Natural History Society of Glasgoiv.
Zoologisch-botanischen Gesellschaft, Wien.
Redia.
U.S. National Museum.
Nuova Notarisia.
Nyt Magazin.
Birmingham and Midland Institute and Scientific Society.
Liverpool Microscopical Society.
Nova Scotian Institute of Sciences.
Royal Dublin Society.
Canadian Institute.
University of California.
Tijdschrift.
Illinois State Laboratory of Natural History.
Scottish Microscopical Society.
The Club's collection of slides has been increased by 133
preparations, including a further donation of fifty Freshwater
Rhizopods from Dr. Penard. An interesting donation consisted
of several fine injected anatomical preparations mounted by the
late Sir Benjamin W. Richardson over fifty years ago, which are
still in perfect condition. It is proposed to publish in future
issues of the Journal lists of additions to the Cabinet, and these
lists will serve as a supplementary catalogue of slides ; the first
list was published in the November issue. Two microscopes with
several objectives and accessories were bequeathed to the Club
by the late J. Mason Allen, so that the Club is now well
provided with microscopes for exhibiting objects at the meetings.
The thanks of the Club are due as in former years to the
editors of the English Mechanic and Knowledge for publishing
excellent reports of the ordinary meetings. Those in the former
journal are of great use in keeping country members au courant
with the doings of the Club.
Your Committee desires to thank the officers for their services
during the past year, and desires to call attention to the
following resolution which was passed by them at their meeting
on January 28th : —
" That the Committee accept with grtat regret the resignation
FORTY-SEVENTH ANNUAL REPORT. 119
of Mr. W. B. Stokes as Secretary of the Club, and in so doing
desire to express their hearty thanks to Mr. Stokes for his
valuable services."
Your Committee sees nothing to prevent the Club maintaining
its traditional usefulness. There is no question as to the need
of such an institution ; but there is need to remind members
of the importance of the Club being all it seems to be to the
new-comer, and not a cause of disappointment. The latter
condition need never obtain if the dual role of the Club be
maintained, presenting an effective means of publicity for the
specialist and a help to the less experienced amateur.
120
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121
ON SOME FORAMINIFERA FROM THE NORTH SEA
DREDGED BY THE FISHERIES CRUISER "HUX-
LEY" (INTERNATIONAL NORTH SEA INVESTIGA-
TIONS—ENGLAND).
By Edward Heron-Allen, F.L.S., F.G.S., F.R.M.S., and
Arthur Earland, F.R.M.S.
{Head March 25th, 1913.)
Plates 10, 11.
In connexion with our paper on the distribution of Psammo-
sphaera and Saccammina in the Northern Area of the North
Sea,* Mr. J. 0. Borley, M.A., of the Fisheries Department,
Board of Agriculture (England), suggested a continuation of our
investigations into the Southern Area. With some reluctance we
undertook the work, having little expectation of any tangible
results, as Mr. Borley had already, from his personal experience
of dredging in these waters, confirmed the generally held belief
that rhizopodal life was of very sparing occurrence in the area
in question. The shallowness of the sea and the consequently
excessive wave action in this area were thought to be factors
limiting the development of rhizopodal life, as compared with
the conditions in the Scottish North Sea, where the average depth
is greater and the disturbance due to the action of waves and
currents is consequently less.
By the courtesy of the officers of the Board the dredgings
made by the Fisheries Cruiser " Huxley " were placed at our dis-
posal, and, guided by the admirable charts plotted by Mr. Borley
to show the distribution of " silt areas " in the North Sea, six
J
* "On some Foraminifera from the North Sea, etc., dredged by the
Fisheries Cruiser " Goldseeker " (International North Sea Investigations —
Scotland). II. On the distribution of Saccammina sphaerica (M. Sars) and
Psa)iimos])haera fusca (Schulze) in the North Sea." Journ. R. Micr. Soc.
1913, pp. K26, pis. i.-iv.
Journ. Q. M. C, Series II. — No. 73. 9
122 E. HERON- ALLEN AND A. EARLAND ON SOME FORAMINIFERA
dredgings were selected, three from the most northerly area
dredged by the " Huxley" and three from an area considerably
farther south.
The three Northerly Stations selected lie far to the N.E. of
the Dogger Bank, in the centre of the North Sea, and in what
is, strictly speaking, the Scottish area of that sea. They lie in
the neighbourhood of the Great Fisher Bank, and are contiguous
to the most southerly line of " Goldseeker" Stations (Stns. 41°,
41B, 41A, 42, etc.) but farther out to sea towards the east. These
three stations are referred to in the following paper as the
Northern or Outer Area.
The three Southern Stations selected lie in the deep trough of
water between the Dogger Bank and the Northumbrian coast,
and are quite close to the shore. They are referred to in the
paper as the Southern or Inner Area.
These dredgings were carefully selected with the view of obtain-
ing the muddiest deposits possible, such conditions being most
favourable for rhizopodal life ; and they probably represent the
richest of the " Huxley " dredgings, all the others which were
cursorily examined consisting of clean siliceous sand with hardly
any trace of microzoa. Such deposits, Mr. Borley assures us, are
typical of the greater part of the Southern North Sea.
Owing to the widely separated stations selected the microfauna
of these six dredgings may probably also be regarded as typical
of the inshore and midsea areas. The comparative richness of
the fauna of the Southern Area, as compared with the Northern,
is undoubtedly due to the proximity of the coastline and the
abundant food supply derived from the coastal deposits.
All the dredgings consisted of loose sands containing a con-
siderable amount of mud ; but whereas the sands from the
Northern Area were easily cleaned (like the majority of the
"Goldseeker" dredgings from adjacent stations), the sands of
the Southern Area proved somewhat refractory. They con-
tained numerous pellets of hardened mud which resisted dis-
integration, and even the action of a strong solution of boiling
FROM THE NORTH SEA. 123
soda did not completely remove the adherent mud from the sand-
grains and foraminifera.
This is a noticeable feature, because as a rule muddy dredgings
are readily broken down if thoroughly dried before the cleaning
process is commenced, and even the most stubborn muds generally
succumb to the action of boiling soda.
We have, however, met with similarly refractory muds at a few
of the " Goldseeker" stations in the Moray Firth, and are unable
to satisfy ourselves as to the cause of this viscosity, which is
quite possibly due to different causes in separate localities.
Among the various explanations which have occurred to us are :
1. The presence of the Hag (Myxine glutinosa). This loath-
some fish is very common at some of the " Goldseeker " stations
where the viscosity has been observed, and as when captured
or touched it exudes an incredible quantity of slime, it is quite
possible that the presence of this fish in any numbers might
locally influence the nature of the sea-bottom. But Mr. Borley
tells us that Myxine is rare in the vicinity of the Stations
sampled, so it may be dismissed from consideration so far as the
" Huxley " material is concerned.
2. Chemical changes in the mud owing to its having passed
through the digestive organs of worms and Echinoderms, many
of which obtain their nutriment by swallowing mud and extract-
ing the organic matter. Thus, in the deep water of some of the
Norwegian fjords, the bottom deposit consists of a very fine
mud full of the tests of rhizopods and swarming with Annelids.
When the mud is dried and broken down again in water, and
the foraminifera have been removed by floating and elutriation,
a mass of fine granular material is left which under the micro-
scope proves to consist of small oval pellets of mud, the excreta
of worms (PL 11, fig. 2).* These pellets resist the action of
soda, making it evident that the mud must have become altered,
* Such deposits are presumably similar to those referred to by Dr. Johan
Hjort under the name of "coprolitic muds." See The Depths of the Ocean,
by Dr. J. Hjort and Sir John Murray (1912), p. 148.
124 E. HERON- ALLEN AND A. EARLAND ON SOME FORAMINIFERA
/
or at any rate that the separate particles must have become
agglutinated during their passage through the alimentary canals
of the worms. Annelid remains are of fairly frequent occurrence
in the "Huxley" dredgings from the Southern Area, but not
noticeably so.
3. It is a matter of common knowledge that fresh mud or
clay, if dried, breaks down readily in water ; but that, if it is
worked or "puddled" before being dried, it becomes plastic, and
then resists disintegration. It is possible that wave or current
action might thus serve to cover the surface of sand-grains and
foraminifera with a coating of mud in a plastic or colloidal
condition, and on the whole we are inclined to favour this
explanation, so far as the viscosity of the " Huxley" deposits is
concerned.
The whole question, however, though interesting from the
point of view of the chemist and physicist, lies rather outside
the province of the zoologist, although it seems evident that the
phenomenon might be of great importance from the geological
point of view, as such viscosity would favour the preservation of
the encrusted microzoa.
A very noticeable feature in the " Huxley " dredgings is the
roundness of the sand-grains as compared with those of "Goldseeker"
dredgings from similar deposits. This is conclusive evidence that
the grains have travelled a great distance, or have been sub-
jected to tidal action within restricted geographical limits for a
prolonged period in comparatively shallow water. The phe-
nomenon has been observed in connexion with the Goodwin
Sands. The scour of the tides and currents round the Dogger
and Great Fisher Banks is doubtless the cause of the rotundity
of the " Huxley " sands, the individual grains of which are often
as smooth and polished as the Aeolian sands of the desert
(PI. 11, fig. 3).*
* Laboratory experiments have proved that a quartz grain -£$ in. in
diameter requires an amount of abrasion equal to that acquired in
travelling- a distance of 3,000 miles in water before it becomes rounded to
the form of a miniature pebble. (Daubree, Geologw Experimentale, Paris,
FROM THE NORTH SEA. 125
To return to the microscopical investigation of the " Huxley "
material : as already stated, this was originally undertaken solely
with the view of extending our study of the distribution of two
species, viz. Psammosphaera fusca (Schulze) and Saccammhut
sphaerica (M. Sars), and the results, so far as they affect those
species, have already been published in our paper dealing with
these forms.* But in the course of an examination of the
material we found so many other forms that we determined to
make a systematic list of the species recorded. This list, which
we now publish, contains no less than 133 species or varieties,
many of which have not been recorded previously from the areas
in question.
It must not be concluded, from the occurrence of so extended
a list, that the material was rich in foraminifera. So far from
this being the case, the majority of the dredgings, previous to
manipulation, gave little or no striking indication of organic
remains beyond the presence of a few shell- fragments, spines of
Echinoderms, annelid tubes, and an occasional rhizopod. The
dredgings quite justified in superficial appearance the opinion
which Mr. Borley and other zoologists familiar with the North
Sea had formed, viz. that it was practically devoid of foraminifera.
But careful and repeated elutriations of the dredgings resulted
in the separation of small quantities of light material at each
station, and, as is often the case, these minute samples yielded
a more diverse fauna than .is often found in richer gatherings.
Except in the case of a few dominant species, however, the
number of actual specimens observed was very small. Even in
the case of the dominant species the proportion of individuals
observed to the total bulk of the dredging was too insignificant
to be estimated. The relative abundance of the species in the
1807, p. 47, and Phillips, Q. J. Geol. Soc, vol. xxxvii., p. 21). But the
dynamics of the troubled waters of the North Sea are probably quite
different from the controlled action of a revolving cylinder in a laboratory
experiment !
* Journ. R. Micr. Soc, 1913, p. 25.
126 E. HERON-ALLEN AND A. EARLAND ON SOME FORAMINIFERA
annexed lists, as indicated by the letters C, R, VR, etc., must
be understood to refer to their abundance as inter-contrasted with
other foraminifera, and not to their frequency in the whole bulk
of the dredging.
A noticeable feature in the dredgings of the Southern or Inner
Area is the relative frequency of specimens of fossil foraminifera.
They are principally small types derived from cretaceous strata
and such as are commonly found in shore sands and shallow-
water dredgings round the southern coasts of England. But a
few larger and well-developed fossil specimens of Nodosaria and
Cristellaria were noted in Hauls 869 and 871, which are not
cretaceous. These are perhaps derived from the Crag, a sub-
marine outcrop of which formation is believed to extend across
the North Sea * ; but they are not all deeply stained with iron,
as is usually the case with the larger foraminifera of the Crag,
and may be derived from the Gault.
Only one fossil was recorded from the Northern Area, viz.
Spirolocidina impressa Terquem. This is no doubt derived from
some submerged Tertiary deposit. It may be noted that Tertiary
foraminifera have been dredged by the " Goldseeker " in the Moray
Firth.
The fossils recorded are :
Spiroloculina impressa Tei quern, Northern Area, one specimen.
Textularia globulosa Ehrenberg, Southern Area, all stations.
Nodosaria pauperata d'Orbigny, Southern Area, two stations.
Nodosaria plebeia Reuss, Southern Area, one station.
Cristellaria costata Fichtel and Moll sp., Southern Area, one
specimen.
Cristellaria rotulata Lamarck sp., Southern Area, one station.
Globigerina aequilateralis Brady, Southern Area, one station.
Globigerina cretacea d'Orbigny, Southern Area, two stations.
* The appearance of many shell fragments dredged from a band of the
sea bed stretching roughly from the Suffolk ccast to the Continent
suggests that they come from the Crag. These, however, are iron-stained
and curiously glazed in appearance in seme, but not in all cases, owing
to attritiop.
FROM THE NORTH SEA.
•~>7
127
One of these species, viz. Cristellaria rotulata Lamarck sp., was
also recorded as a recent form.
An examination of the list of species at the different stations
reveals several noticeable features. Taking the three stations in
the Northern Area first, it will be seen that they vary greatly
in richness, Haul 767 yielding only 14 species, as against 26 in
Haul 770 and 54 in Haul 772. Even the richest haul in the
Northern Area contrasts badly with the poorest haul in the
Southern Area, which yielded 72 species, the other Southern
hauls yielding 79 and 94 species respectively.
This discrepancy is largely explained by the abundant records
of the Family Lagenidae in the Southern Area. The figures are
very striking, fossils being disregarded :
Northern Area.
Southern Area
Lagena .
8
30
Nodosaria
—
3
Lingulina
—
1
Margin ulina
—
1
Vaginulina
—
1
Cristellaria
—
2
Polymorphina .
2
4
Uvigerina
2
2
Total
12
44
The abundance of Lagenidae in this Area off the Northumber-
land coast has already been noted by Brady.* But in the
" Huxley " dredgings only the genus Lagena is noticeably
abundant, the other genera of the family not being well
represented.
The other families exhibit a similar discrepancy in the lists of
species recorded from the two Areas, but it is not so noticeable
as in the case of the Lagenidae.
* Report British Association, 1862, p. 122; also Trans. Tyneside
Naturalists Field Club, 1863, vol v., part 4, p. 292; Ibid., 1864. vol. vi.,
part 2, p. 194.
128 E. HERON-ALLEN AND A. EARLAND ON SOME FORAMINIFERA
The dominant forms in the two Areas are as follows * :
Northern.
8. Miliolina seminulum Linne
sp.
21. Reophax sco?yiurus Mont-
fort.
26.
37.
42.
69.
82.
97.
100.
106.
118.
123.
124.
126.
132.
Verneuilina polystropha
Reuss sp.
Bulimina fusiformis W ill .
Polymorphina compressa
d'Orbigny.
Polymorphina sororia
Reuss.
Truncatulina lobatula W.
& J. sp.
Rotalia Beccarii Linne sp.
Nonionina depressula W.
& J. sp.
Polystomella striatopunc-
tata F. & M. sp.
Southern.
Miliolina seminulum Linne sp.
Reophax scorpiurus Montfort.
Haplophragmiiim p>se udosp irale
Will. sp.
Verneuilina polystropha Reuss
sp.
Bidimina fusiformis Will.
Lagena laevigata Reuss sp.
Lagena striata d'Orbigny sp.
Globigerina rubra d'Orbigny.
Truncatulina lobatula W. & J.
sp.
V C at one station only.
Rotalia orbicularis d'Orbigny.
Nonionina depressula W. & J.
sp.
Polystomella striatopunctata F.
& M. sp.
Several of these forms are more abundant in one Area than in
the other, as may be seen by reference to the table.
Some of the discrepancies in the above comparative list can be
explained by what we know of the distribution of the species in
other rhizopodal faunas. Thus (26) Haplophragmiiim pseudo-
spirale Will. sp. (PI. 10, fig. 2-4) appears to be confined to coastal
deposits. It is very common in many muddy shallow-water
dredgings round the W. coast of Ireland and Scotland and in
the Shetlands, but the u Goldseeker " records in the North Sea are
* The numbers refer to the tabular list at the end of the paper.
FROM THE NORTH SEA. 129
very few and entirely confined to coastal gatherings. It does not
occur in any of the midsea " Goldseeker " dredgings from stations
adjacent to the Northern Area of the " Huxley"
Of the other species recorded in the list a few have more than
a passing interest. (1) Nubecularia lucifuya Defrance is a southern
form, not previously recorded on the S. and E. coast of Britain
beyond Bognor, Sussex. A few specimens have been dredged by
the "Goldseeker " in the Moray Firth and Shetland seas, and these
two records, from intermediate localities, are therefore of interest.
The same remarks apply to (9) Massilina secans d'Orbigny sp.
This is the most abundant and typical Miliolid of the shore
sands and shallow water all round the S. and W. coast-line.
There are few records of shore sands on the E. coast, but the
species occurs at Cromer and St. Andrews (Fife) and is abundant
at Scapa in Orkney in shore sand. It is extremely rare in the
" Goldseeker ■'" North Sea dredgings, but the few specimens found
were from a Station (39B) near the " Huxley " Northern Area.
Its absence from the Southern Area is noticeable, and probably
due to the muddiness of the deposit.
(12) Comuspira striolata Brady. The specimen from Haul 767
(Northern Area) is of the very fragile and etiolated type abun-
dant in many of the " Goldseeker " dredgings from the deeper
North Sea.
(13) Comuspira diffusa Heron- Allen and Earland * (P\. 11,
fig. 1). The specimens of this form, which has been recently
described by us, were large and quite typical, but few in number.
The Northern Area is quite close to the " Goldseeker " Stations at
which it is most abundant, but the species is sparingly distributed
round the British coast.
(14) Bathysiphon argenteus, (62) Layena cymbula (PL 10,
figs. 10-12), (84) Layena unyuis, and (117) Discorbina Praeyeri
* " On some Foraminifera from the North Sea, etc., dredged by the
Fisheries Cruiser. " Goldseeker " (International North Sea Investigations —
Scotland). III. On Comuspira diffusa, a new type from the North Sea."
Journ. R. Mior. Soc., 1913, pp. 272-6, pi. xii.
130 E. HERON-ALLEN AND A. EARLAND ON SOME FORAMINIFERA
are new forms discovered first by us in " Goldseeker " dredgings.
They are described and figured in our report on the Foraminifera
of the Clare Island Survey (Proc. Roy. Irish Acad., 1913, vol. xxxi.,
No. 64).
(20) Reophax nodulosa Brady (PI. 10, fig. 1) is extremely
rare as a British species. It has been recorded from the Clyde
Area and Skye by Robertson and from the Estuary of the Dee
by Siddall. The British specimens are very minute, but in the
deep sea it attains a great size, up to 1 in. in length.
(23) Haplophragmium anceps Brady, another deep-water form,
is of rare occurrence in British waters. It has been recorded
from shore sands at Southport (Chaster) and Bognor (Earland),
and we have recently dredged it in the Clare Island Area.
(25) Haplophragmium crassimargo Norman (PL 10, fig. 5-6),
a large and very robust form closely allied to H. canariense
d'Orbigny sp., is the typical Haplophragmium of the deeper parts
of the North Sea, and is abundant in many of the " Goldseeker "
dredgings.
(27) Thurammina papillata Brady. The single specimen re-
corded from Haul 369 in the Southern Area is extremely small,
but quite typical of the spherical type (cf. Brady, Foraminifera
of the u Challenger" 1884, pi. xxxvi., fig. 7). The papillae are
prominent and very numerous. The genus Thurammina is
abundant and very variable in the deep water of the North Sea
to the N.E. of Shetland, but very rare in the central North Sea.
(28) Ammodiscus incertus d'Orbigny. All the specimens are
very minute and of a light-grey colour. The genus is very
sparingly distributed in all the " Goldseeker " dredgings from the
North Sea, and all the specimens are minute. In the Faroe
Channel, however, it attains its full dimensions.
(35) Spiroplecta biformis Parker and Jones sp. (PI. 10,
fig. 9). The single specimen of this rare form, recorded from
Haul 772 in the Northern Area, is noticeable for the rapid
increase in size of the Textularian chambers following the Spiro-
plectine portion of the test.
FROM THE NORTH SEA. 131
(37) Vemeuilina polystropha Reuss sp. All the specimens of
this species, one of the most abundant and typical North Sea
forms, belong to the large coarsely built type, except in Haul 770
Northern Area, where also a few individuals of the minute and
delicate type described and figured by us in the Clare Island
Survey Report were observed.
(38) Clavulina obscura Chaster (PI. 10, figs. 7, 8), occurs in
both Areas, but whereas the Northern Area yielded only a single
specimen, the species attains an extraordinary development both
as regards size and abundance in Haul 871 in the Southern
Area. It is usually a very rare species, though widely distributed
round our coasts in muddy gatherings.
(91) Lingulina carinata d'Orbigny. The single specimen from
Haul 869 Southern Area is of a minute type. Such specimens
occur sparingly in most of the " Goldseeker" dredgings from
muddy areas.
(92) Marginulina glabra d'Orbigny. The single specimen from
Haul 871 is very minute. Rut the species is abundant and
attains a very large size in the deeper waters of the North Sea
to the N.E. of Shetland.
(106) Globigerina rubra d'Orbigny (PI. 10, figs. 13-15). This
species is one of the commonest Globigerinae all over the North
Sea and often forms a large proportion of the finer material
dredged on muddy bottoms.
(110) Discorbina Chasterl Heron-Allen and Earland. Origin-
ally described by the late Dr. Chaster of Southport under the
specific name Discorbina minutissima. This specific name having
been previously used by Seguenza for another form, we have
(in the Report on the Foraminifera of the Clare Island Survey)
renamed the species after its original discoverer. It is of common
occurrence in muddy dredgings from all the shallow coastal
deposits of the North Sea and around the Western shores of
Britain generally.
(112) Discorbina Mediterranensis d'Orbigny sp. and (115) Dis-
corbina Peruviana d'Orbigny sp. are old specips which we propose
132 E. HERON-ALLEN AND A. EARLAND ON SOME FORAMINIFERA
to revive for sub-types of the " rosacea " group, under a scheme
which is fully explained in our Clare Island Report.
(133) Polystomella crispa Linne sp. The occurrence of only a
single specimen of this species in the Southern Area is very
noticeable, as it might have been expected to occur more plenti-
fully so near the coast. But as regards the single specimen from
the Northern Area, its occurrence there is still more noteworthy,
as the species is extremely rare in the " Goldseeker " dredgings
even in the proximity of the coast and none have been previously
found so far out at sea as this. The specimen is, however,
very water- worn, and may have been current-borne for a great,
distance.
List of " Huxley " Stations from which Material
was Examined.
(
A. Northern or Outer Area — lying N.N.E. of the Dogger
Bank.
1. Haul 767, Station xix., 56° 53' N., 3° 43' E. Dredging made
July 22nd, 1906, in 35 fathoms, to the S.W. of the Great
Fisher Bank.
2. Haul 770, Station xxii., 56° 50' N., 3° 59' E. Dredging made
July 24th, 1906, in 31 fathoms, on the Inner Shoal to the
S. of the Great Fisher Bank.
3. Haul 772, Station xxv, 56° 34' N.', 3° 53' E. Dredging made
July 24th, 1906, in 37 fathoms, to the S. of the Inner
\ Shoal and Great Fisher Bank.
/ B. Southern or Inner Area — lying W. of the Dogger Bank,
between the Bank and the English coast.
4. Haul 869, Station xlii., 55° 6' N., 1° 2' W. Dredging made
July 23rd, 1907, in 43 fathoms, off Blyth, Northumberland.
5. Haul 871, Station xliv., 54° 59' N., 1° 7' W. Dredging made
July 23rd, 1907, in 34 fathoms, off Tynemouth.
6. Haul 882, Station (?), 55° 21' N., 1° 10 'W. Dredging made
\ July 26th, 1907, in 45 fathoms, off Alnmouth.
FROM THE NORTH SEA.
133
The asterisk denotes the presence of fossil specimens. 1 = a single
specimen only. V C = very common. C = common. F == frequent. R =
rare. VE = very rare.
MlLIOLIDAE.
Sub-family Nubecv larinae.
1. Xubecularia lucifuya Def ranee
Sub-family Miliolin inae.
2. Biloculina depressa d'Orbigny
3. Biloculina rinyens Lamarck sp.
4. Spiroloculina impressa Terquem
5. Miliolina bicomis Walker & Jacob sp
6. Miliolina circularis Bornemann sp.
7. Miliolina contort a d'Orbigny sp.
8. Miliolina seminulum Linne sp.
9. Massilina secans d'Orbigny sp.
Sub-family Pen eroplid inae.
10. Cornuspira involvens Reuss
11. Cornuspira Seise ye nsis Heron- Allen &
Earland ......
12. Cornuspira striolata Brady
13. Cornuspira diffusa Heron-Allen & Ear-
land
ASTRORHIZIDAE.
Sub-family Pilvlin inae.
14. Bathy siphon aryenteus Heron-Allen &
Earland
Sub-family Saccammininae.
15. Psammosphaeva fusca Schulze
16. Saccammina sphaerica M. Sars
Sub-family Bhabdamm in i nae.
17. Hyperammina ramosa Brad}r .
LlTUOLIDAE.
Sub-family Litvolinae.
18. Beophax dipluyiformis Brady
19. Beopha.v fusiformis Williamson sp.
20. Beophax nodulosa Brady
21. Beophax scorpiurus Montfort
22. Beophax Scottii Chaster
23. Haplophraymium anceps Brady
24. Haplophraymium Canariense d'Orbignv
sp
25. Haplophrayminm crassimargo Xorman
26. Haplophraymium pseudospirale William
son sp. .....
vc
c
vc
VR
VC
F
R
1*
c
vc
2
F
VC
R
1
VC
vc
F
1
1
5^:
03 so
1
2
VR
R
F
VC
VR
VR
VC
5_-
F
R
R
2
VC
VC
1
VC
C
VR
VC
F
1
e
vc vc
3d
VR
VC
1
1
VR
134 E. HERON-ALLEN AND A. EARLAND ON SOME FORAMINIFERA
i
Sn
go
P <N
p®
3^'
3«
c3 ro
c3 t-
rit~
ci co
« r-
=5 oo
£r-
B"
si-
K=°
w°°
K00
1
'.
2
3
4
5
6
Sub- family Trochammin inae.
27. Thurammina papillata Brady
1
28. Ammodiscus incertus d'Orbigny sp.
R
F
29. Trochammina ochracea. Williamson sp. .
F
C
R
vc
30. Trochammina squamata Jones k, Parker
F
VC
Textularidae.
Sub-family Textv lari nae.
31. Textularia agglutinans d'Orbigny .
VR
32. Textularia conica d'Orbigny .
VR
VR
vc
33. Textularia globulosa Ehrenberg
Y*
F*
1*
34. Textularia gramen d'Orbigny .
VR
35. Spiroplecta biformis Parker & Jones sp. .
1
36. Gaudryina filiform in Berthelin
-
F
R
37. Yerneuilina polystropha Reuss sp.
vc
R
VC
VC
VC
VC
38. Clavulina obscura Chaster
1
F
VC
Sub-family Bu limin inae.
39. Bulimina aculeata d'Orbigny
VR
R
c
40. Bulimina elegans d'Orbigny .
► •
F
C
R
41. Bulimina elegantissima d'Orbigny
c
R
F
42. Bulimina fusiformis Williamson
vc
C
vc
VC
VC
VC
43. Bulimina marginata d'Orbigny
c
F
c
F
F
C
44. Bulimina, ovata d'Orbigny
F
45. Bulimina pupoides d'Orbigny
R
R
1
46. Virgvlina Schreibersiana Czjzek
R
R
47. Bolivina difformis Williamson sp.
VR
VR
1
48. Bolivina dilatata Reuss .
R
C
C
49. Bolivina nobilis Hantken
1
1
50. Bolicina plicata d'Orbigny
1
VR
F
F
51. Bolivina punctata d'Orbigny .
C
R
F
F
52. Bolivina textilarioides Reuss .
R
53. Bolivina variabilis Williamson sp.
R
F
Sub-family Cassibulin inae.
54. Cassidulina crassa d'Orbigny .
F
F
F
F
55. Cassidulina laevigata d'Orbigny
VR
R
1
56. Cassidulina subglobosa Brady.
R
R
F
Lagenidae.
Sub-family Lag en inae.
57. Lagena acuticosta Reuss
VR
58. Lagena apiculata Reuss sp. .
VR
2
59. Lagena bicarinata Terquem sp.
1
60. Lage?ia clavata d'Orbigny sp.
R
C
F
61. Lagena costata Williamson sp.
F
R
62. Lagena cymbula Heron-Allen & Earland
1
63. Lagena distoma Parker & Jones
1
R
C
VC
64. Lagena fasciata Egger .
R
VR
1
65. Lagena globosa Walker & Jacob sp.
1
VR
F
1
66. J^agena gracUlima Seguenza sp.
j
1
C
FROM THE NORTH SEA.
135
"'-' 5® 3<* 2
~*- Sl- K1- K
67. Lagena
68. Lagena
69. Lagena
Lagena
79. Lagena
71. Lagena
Lagena
72. Lagena
73. Lagena
74. Lagena
75. Lagena
76. Lagena
77. Lagena
78. Lagena
79. Lagena
80. Lagena
81 Lagena
82. Lagena
83. Lagena
84. Lagena
85. Lagena
gracilis Williamson .
hexagona Williamson sp.
laevigata Reuss sp. .
laevigata, trigonal form
laevis Montagu sp.
lagenoides Williamson sp.
lagenoides, trigonal form.
lineata Williamson sp.
lucid a Williamson sp.
Malcomsonii J. Wright
marginata Walker & Boys sp.
marginato-perforata Seguenza
Orbignyana Seguenza sp.
ornata Williamson sp.
quadrata Williamson sp.
se mist riat a Williamson
squamosa Montagu sp.
striata d'Orbigny sp. .
sulcata Walker & Jacob sp.
unguis Heron-Allen *Sc Earland
Williamsuni Alcock sp.
Sub-family Xodosarinae.
86. Xodosaria Jiliformis d'Orbigny
87. Xodosaria pan perata d'Orbigny
88. Xodosaria pltbeia Reuss.
89. Xodosaria p grula d'Orbigny .
90. Xodosaria scalaris Batsch sp.
91. Lingulina carinata d'Orbigny
92. Marginulina glabra d'Orbigny
93. Vaginuliiia legumen Linne sp.
94. Cristellaria acut auricular is Fichtel &
Moll sp
95. Cristellaria costata Ficbtel & Moll sp.
96. Cristellaria rotulata Lamarck sp. .
Sub-family Poltmorp hi n inae.
97. Polgmorphina compressa d'Orbigny
98. Polgmorphina lactea Walker & Jacob sp
99. Polgmorphina oblonga Williamson .
100. Polgmorphina sororia Reuss .
101. T'vigerina angulosa Williamson
102. Ucigerina pygmcea d'Orbigny
Olobigerixidae.
103. Globigerina aequilateralis Brady .
104. Globigerina bulla ides d'Orbigny
105. Globigerina cretacea d"Orbigny
106. Globigerina rubra d'Orbigny .
107. Pullenia xphaeroides d'Orbigny sp.
VC
1
R
ve
c
R
YC
F
F
F
VC
VC
1
1
R
1
VR
VE
C
VR
R
VR
VR
VR
1
VR
F
VC
VR
F
1*
R
1
VR
1
1*
R*
R
1
R
C
Y*
VC
X — X
1
F
VC
c
VR
F
F
F
1
F
1
C
F
C
C
1
c
1
1*
\TR*
1
2
1*
R
1*
C
1
VC
F
1
1
1
F
F
VC
C
R
C
1
c
R
VC 1
R
R
C
C
1
136 B. HERON-ALLEN AND A. EARLAND ON SOME FORAMTNIFERA
ROTALIDAE.
Sub-family Spj rillin inae.
108. Spirillina vivipara Ehrenberg
Sub-family Rotalinae.
109. Patellina corrugata Williamson
110. Discorbina Chasteri Heron-Allen & Ear-
land ......
111. Discorbina globularis d'Orbigny
112. Discorbina Mediterranensis d' Orbigny sp
113. Discorbina nitida Williamson sp. .
114. Discorbina obtusa d'Orbigny sp.
115. Discorbina Peruviana d'Orbigny sp.
116. Discorbina poly rraphes Reuss
117. Discorbina Praegeri Heron- Allen & Ear
land ......
118. Truncatulina lobatida Walker & Jacob
sp. .....
119. Truncatulina refulgens Montfort sp.
120. Truncatulina Ungcriana d'Orbigny sp,
121. Pulvimdina haliotidea Heron-Allen &
Earland .....
122. Pulvinulina Karsteni Reuss sp.
123. Rotalia Beccarii Linne sp.
124. Rotalia orbicularis d'Orbigny
NUMMULINIDAE.
Sub-family Poltstomellinae.
125. Nonionina asterizans Fichtel & Moll sp.
126. Nonionina depressula Walker & Jacob
SP
127. Nonionina pauper ata Balkwill & Wright
128. Nonionina scapha Fichtel & Moll sp.
129. Nonionina stelligera d'Orbigny
130. Nonionina turgida Williamson sp. .
131. Nonionina umbilicatula Montagu sp.
132. Polystomella striatopunctata Fichtel &
Moll, sp
133. Polystomella crispa Linne sp.
3*-'
VC
3®
c
vc
vc
F
F
R
C
VC
vc
1
3«
F
F
1
VC
R
C
C
R
VC
VC
2*'
VR
VR
C
F
R
VC
VR
C
1
VR
1
R
1
VR
C
R
C
R
C
F
C
C
VR
F
VR
VC
F
F
R
R
1
VC
«« CO
£cc
c
1
1
c
1
R
C
F
1
R
C
1
F
1
F
C
FROM THE NORTH SEA. 137
DESCEIPTION OF PLATES.
Plate 10.
Fig. 1. Reophax nodulosa Brady, x 120.
„ 2, 3, 4. Haplop>hragmium pseudospi?*ale Will, sp., x 40.
,, 5, 6. Haplophragmium crassimargo Norman, x 30.
,, 7, 8. Clavulina obscura Chaster, x 100.
„ 9. Spiroplecta b iformis Parker & Jones sp., x 120.
„ 10. Lagena cymbida Heron- Allen & Earland, superior view,
X 250.
„ 11. Lagena cymbida Heron- Allen & Earland, inferior view,
x 250.
,,12. Lagena cymbida Heron-Allen & Earland, edge view,
x 250.
„ 13, 14, 15. Globigerina rubra d'Orbigny, x 120.
Plate 11.
Fig. 1. Cornuspira diffusa Heron-Allen & Earland, x 5, illus-
trating the protean habit of growth.
„ 2. Heavy portion of ooze from Hilte Fjord, Norway, 260
metres, " Goldseeker" Haul 141, depth 260 metres.
Most of the foraminifera have been removed by
elutriation, leaving a residuum of faecal pellets of
Annelid origin (1 Hyalinoecia sp.) x 45.
,, 3. Rounded sand-grains from "Huxley" material, x 12.
,, 4. Normal angular grains typical of shore gatherings and
shallow-water deposits, x 12.
,, 5. Crystalline sand-grains from a dredging in the Hauraki
Gulf, New Zealand, x 1 2. Such crystalline grains are
very rare except in the neighbourhood of volcanic
deposits.
[It is greatly to be hoped that the writers will find it possible
for them to examine in similar detail a certain number of the
remaining "Huxley" dredgings, of which some six hundred are
available, taken from the North Sea south of the Forth. Their
present paper shows that in their practised hands results of con-
siderable interest may be expected should this be done. I would
Journ. Q. M. C, Series II.— No. 73. 10
138 E. HERON-ALLEN AND A. EARLAND ON SOME FORAM1NIFERA.
submit for their consideration the examination of selected stations
along lines drawn east and west, in the manner of sections. A
large proportion of these in all probability could be dealt with
in a very summary manner, but the remainder might yield
results of importance as to the relation of distribution to salinity,
depth, temperature and current, possibly even affording evidence
of the main trend of the currents, which would provide a welcome
check on other observations carried out by current-meters and
drift -bottles.
In regard to the samples which they have examined from
the deep water east of the Dogger it may be remarked that the
Admiralty tide charts show but low rates of velocity in the
district, which has moreover a greater depth of water than one
would expect to be consistent with frequent wave action at the
bottom. Recent current measurements carried out by the
Board of Agriculture and Fisheries have also failed to detect
any marked resultant current. It may therefore be suggested
that the sub-polish attained by the rounded grains is not in
all cases due to attrition on the spot. The freedom of the
adjacent Dogger Bank from silt, a grade of material found in
high percentage on either side, may perhaps be explained by
the finer particles churned up and held in suspension by wave
action during storms being gradually washed into the deeper
water : some segregation of the rounder grains may take place
in the same manner. A thorough geological examination of
the area, especially of the Scottish coast, might also show to
what extent, if any, the grains result from the disintegration
of certain definite sandstone rocks.
For the action of wave and current in the Southern Bight
(North Sea south of 53°) the collection of samples as a whole
furnish good evidence ; the material is to a great extent graded
as in a levigator, the average diameter of the sand particles
diminishing as the speed of the current declines. Yet even in
this district, with its shallower waters and far more powerful
currents, the upper limit of size of the particles affected is soon
reached, and one feels in consequence the need of searching for
other causes before explaining the rotundity of certain of the
grains near the Dogger by tidal action alone. — J. O. Borley.]
r— . , . _____ _ , _,
jQurn. Quefcett Mkyo-icopical CliLib, Ser. 2, YoLX.IL, Np. 73, November ]£>Z3,
Journ. Q.M.C.
Ser. 2, Vol. XII., PI. 10.
FORAMINIFERA FROM THE NORTH SEA,
Tourn. Q.M.C.
Ser. 2, Vol. XII., PI. 11.
BpX^Smt
N ■ •
A^fc. ^*> ^? 1
P>
',.
*^ . -
IF
i^E^L^^
.4
t?
P^B . a^P^H P^PAw^a. .^^Pmb ^■■1 P^H t» *^? 1
^^^■B PMV «■ PS -k^_ fi^W
Bp^^^ r m ^ J
BS^; Kpjfe/w ^^^^ Pfet. ^
W*iM PJ*V»^ PA. •3L ■> Bl
4 fe^ ^
CORNUSPIRA DIFFUSA HERON-ALLEX AND EaRLAND.
Sand-grains, etc., from the Bottom-deposits,
139
DESCRIPTION OF ARRHENURUS SOOURFIELDI AND
ACERCUS LONG/TARSUS : TWO NEW SPECIES OF
WATER-MITES.
By C. D. Soar, F.L.S., F.R.M.S.
(Read April 22nd, 1913).
Plates 12, 13.
Arrhenurus Scourfieldi sp. nov.
In the autumn of 1912, Mr. D. J. Scourfield handed me a tube
containing a few water-mites, which he had taken from fresh
water in Cornwall. Amongst them was one which was quite new
to me, a male Arrhenurus, of the sub-genus Megalurus. As I
cannot find that it has been described or figured, I propose to name
it after Mr. Scourfield.
Arrhenurus Scourfieldi sp. nov. — The specimen is a male ;
length 1-04 mm., greatest breadth about 064 mm. In outline
the body is long ; anterior corners well cut off, and slightly bent
inwards ; sides almost straight, tapering towards the posterior
margin. The posterior margin is divided by a central cleft into
two well-rounded portions.
The skin is covered with small papillae ; the dorsal surface has
the usual indented sunk line common to members of this genus,
and several dermal glands both inside and outside the sunken line.
Looked at from above there is a small wing-like process about
0'15 mm. from the posterior margin.
The colour is a dark blue-green with brown markings on the
dorsal surface. The epimera are slightly lighter in colour. It
is of the same colour as Arrhenurus globator.
The eyes are very dark red, close to margin, about 0*32 mm.
apart. Capitulum, about 0"20 mm. long.
The first pair of epimera are joined together at the back of the
capitulum, the second pair pressed close to first pair so that what
140 C. D. SOAR, DESCRIPTION OF ARRHENURUS SCOURFIELDI AND
is known as the first two pairs of the epimera form one distinct
group.
The posterior pair are in two distinct groups placed about
0*05 mm. behind the second pair.
The genital area lies about 0*08 mm. behind the fourth pair of
epimera, the plates stretching the whole distance across the
body of the mite. The length of each plate is about 0*25 mm.,
tongue shaped and covered with numerous acetabula.
The legs are of the usual structure of the genus with the spur
on the fourth segment of the fourth leg. They are strong and
well provided with swimming hairs. The first leg about 0"60 mm.
long, fourth leg 0'84 mm.
Locality : Near the Lizard, Cornwall, 1912. Female unknown.
Acercus longitarsus sp. nov.
Acercus longitarsus sp. nov. — The body is 0*76 mm. in length ;
breadth about 0'54 mm., ovate. The colour is a pale straw
yellow with dark-brown markings. There is a reddish-yellow
wedge-shaped patch in the centre of the dorsal surface.
The epimera cover nearly the whole of the ventral surface, and
differ from that of the type species Acercus omatits in the follow-
ing important particulars. Firstly, the genital area instead of
being situated in a small bay on the posterior margin of the
epimera as in Acercus ornatus, is partly enclosed in an angular
space formed by the posterior edge of the epimera being turned at
a low angle towards the median line. Secondly, near the base
of the epimera are two small incurvations, one on each side, which
are not found in the type species of this genus. They run into
the epimera about O05 mm. The actual genital area itself is
similar to type species, having six acetabula arranged in the same
way.
The palpi are about 0*45 mm. in length. On the flexar edge
of the fourth segment are placed two long hairs, a little distance
apart ; they are close together in Acercus ornatus.
The legs of the species form the most striking departure from
the type form and in fact all other species of this genus ; on
comparison it will be seen that the tarsi are enormously developed
in length.
The last segment of the first and second pairs of legs are longer
ACERCUS LONGITARSUS \ TWO NEW SPECIES OF WATER-MITES. 141
than usual, but it is the last segment of the fourth pair which
shows the great increase in length. The tarsi measure as much
as 0*60 mm., which is more than the fourth and fifth segment
together.
The first leg is about 1*40 mm. in length, the second about 1*30,
the third about 0"90, the fourth about 1-58.
The eyes, large and distinct, are very dark red and about 0'14
mm. apart.
This mite can be most easily recognised by the length of the
tarsus of the fourth pair of legs. I propose naming it Acercus
longitarsus.
Locality : South Devonshire (female unknown).
There are also one or two additions to be made to British
records. Mr. Williamson, F.R.S.E., in working out the material
on the Genus Sperchon, has found that we have two species quite
new to the British area, and two that up to the present have only
been recorded for Ireland.
1st. Sperchon clupeifer Pier.
Sub-genus : Hispidosperchon.
Locality : Oban and Norfolk Broads.
2nd. Sperchon tenuabilis Koen.
Sub-genus : Hispidosperchon.
Locality : Oban. Recorded for Ireland by Halbert in Clare
Island survey.
3rd. Sperchon papillosus Sig Thor.
Sub-genus : Squamosus.
Locality : Oban. Recorded for Ireland by Halbert.
4th. Sperchon Thienemanni Koen.
Sub -genus : Rugosa.
Locality : Derbyshire.
142 c. d. soar, description of two new species of water-mites.
Description of Plates.
Plate 12.
Fig. 1. Arrhenurus Scourfieldi sp. nov. — Dorsal surface of male
drawn from a living specimen, x 50.
„ 2. Arrhenurus Scourfieldi sip. nov. — Ventral surface of same
drawn after mounting.
Plate 13.
Fig. 1. Acercus longitarsus sp. nov. — Dorsal surface of males,
X 58.
„ 2. Acercus longitarsus sp. nov. — Ventral surface of same,
x 58.
„ 3. Acercus longitarsus sp. nov. — Palpi of same, X 150.
Jovrn. Quelett Microscopical Club, Ser. ?, Vol. XII., Ho. 73, November 1913
Journ. Q.M.C.
Ser. 2, Vol. XII., PI. 12.
^A7 2
C. D. S., del. adnat.
$ Arrhenurus Scourfieldi sp. nov.
Journ. Q.M.C.
Ser. 2, Vol. XII., PI. 13.
C. D. S., del. ad nat.
S ACERCUS LONGITARSUS sp. nOV.
143
THE COLLECTION AND PRESERVATION OF THE
HYDROIDA.
By G. T. Harris.
Communicated by C. J. IT. Sidwell.
{Bead April 22nd, 1913.)
The Hydroida are too well known, as both beautiful and interesting
objects, to need any eulogy on my part. If they have received
less attention from the members of the Q.M.C. than some other
groups, it is probably due to the fact that the Hydroida evince
a decided and conservative preference for salt water, and show
no inclination whatever for the uneventful environment of
metropolitan ponds. Hence, those who would collect them must
seek them where they may be found, i.e. from tidal limits to as
many fathoms as the collector's means or stomach will allow.
Bearing in mind that this paper is written more for the help
of the novice than as a communication offering original matter,
I would safeguard myself from any charge of carelessness by
warning the uninitiated that collecting, say, rotifers, and col-
lecting hydroids are two totally dissimilar things. Pond
collecting is a more or less safe and a very pleasant recreation ;
hydroid collecting is rarely enjoyable, and may be, by a little
carelessness, rendered adventurous. The one could be prosecuted
in a silk hat and a frock coat if desired, without seriously giving
the wearer away ; the costume best suited to the other tries the
loyalty of one's staunchest friend. Dredging is, perhaps, less
open to contumely than shore collecting ; the nature of the
operation secures to the collector a considerable measure of
privacy, while the examination of the spoil can be carried out
in attitudes familiar to oneself and those around. Shore collect-
ing permits of no compromise, and the positions most consonant
with successful collecting are mainly such as contribute materially
to the entertainment of the seaside visitor waiting to be
amused.
I think it may be taken for granted that, in spite of its
144 G. T. HARRIS ON THE COLLECTION AND
obvious drawbacks, shore collecting will appeal to the amateur
collector rather than the more professional method of dredging.
It entails less expense, requires less intimacy with the local
conditions, and, for a given amount of time expended, probably
yields a richer harvest ; finally, the physiological effects of shore-
collecting are not so overwhelming as are those sometimes
connected with dredging. At the same time, no serious student
of the Hydroida can ignore the dredge as a means of collecting,
as a large number of species can only be obtained by its aid.
However, for the reassurance of those who confine themselves to
shore collecting, I may state, as the result of long experience,
that on a favourable shore the number of species to be found
between tide-marks is very great, and amongst them are many of
the most beautiful forms amongst the Hydroida. -
Unfortunately no precise directions can be given for successful
shore collecting. It is entirely a matter of experience, and even
the practised collector may fail dismally until he has learnt the
shore upon which he is engaged. Why hydroids should be found
plentifully in a certain section of shore, yet be absent from the
same shore a quarter of a mile away, with apparently the same
conditions, I am unable to say, yet such appears to be the case. In
my own district, where rock-pools are plentiful, I have a case
in point. Coryne vaginata, one of the commonest littoral
hydroids along the south coast, occurs in two or three of the
larger pools of a certain locality, yet although the rock-pools to
the right and left for some distance are, as far as I can see,
identical, no Coryne occurs in them. Nor is this accidental, or
peculiar to one season, as I have been able to go to these
particular pools for the last six years with the certainty of
obtaining Coryne vaginata. Some years ago when collecting at
Criccieth, in North Wales, I spent day after day laboriously
trying to collect hydroids where none grew ; finally, I transferred
my operations to a less likely looking section of the shore, and
collected hydroids during the remainder of my visit over a very
limited area. An instance singularly illustrative of this elusive
quality of shore collecting recently came under my notice, which
may serve to impress upon inexperienced collectors the desirability
of not jumping too hastily to the conclusion that they are on a
barren shore. A party of professional naturalists spent the
whole of one summer in investigating the fauna of a certain
PRESERVATION OF THE HYDRQIDA. 145
section of coast, the results of which were embodied in a report.
The shore collecting was apparently confined to one spot, from
which but one hydroid, and that the ubiquitous Sertularia pamila,
was recorded ; yet a quarter of a mile farther east is an excep-
tionally prolific hunting-ground at low tide, where at least a
dozen species of hydroids may be taken. All this points to the
fact that wherever the hydroid-hunter elects to collect he must,
as a preliminary, first ascertain that he has found the hydroid
ground. When he has satisfied himself that he has done so, then
collecting may begin in earnest.
It is too readily assumed that only those shores are good for
hydroid-hunting upon which rock-pools occur. My experience
leads me to protest against this assumption, for I have often
had much better collecting on shores strewn with large fucus-
covered boulders than in some rock-pool districts. Rock-pools do
not necessarily imply the existence in them of hydroids, not even
when they are clean, sanitary abodes. The rock-pools at Sid-
mouth are excavated in Permian sandstone at the base of cliffs
500 ft. high, composed principally of Keuper marl, and in the
early summer are lined, as is everything in them, with fine
mud, the result of the red marl falling from the cliffs during
winter and being washed into the pools. This should make
hydroid life impossible, but it does not ; they seem to thrive in
it (I sometimes think upon it), and cleaning them for the
microscope thoroughly disheartens one. Last autumn I was
collecting in South Devon, where the cliffs are composed of
hard conglomerate, giving fine clean rock-pools. One rock-pool
near low-water mark especially attracted my attention. Filled
with clear, limpid water, its sides draped with seaweeds, every
condition seemed perfect for hydroid life, and yet not a single
specimen was found in it. I satisfied myself of this by abso-
lutely cleaning the pool out, examining every piece of seaweed,
as I removed it, in a small tank of water, then going carefully
over the sides and bottom of the pool with a lens of large
diameter. It is little discrepancies like these that both try and
puzzle the shore collector.
Hincks has given advice upon shore collecting that cannot
well be improved upon, and is as precise as such advice can
be. He recommends lying at full length when collecting, and
however objectionable this may seem to be in theory, it is
146 G. T. HARRIS ON THE COLLECTION AND
thoroughly sound in practice, and I always adopt it, carrying
a mackintosh sheet for the purpose. It should be recollected
that a superficial examination of any rock-pool is not sufficient
to detect minute species, and even species of considerable size,
such as Plumularia setacea, often harmonise so well with their
surroundings as to be difficult of detection. As far as possible
it is best to assume a comfortable position, and then thoroughly
examine the basin and the seaweeds it contains, using a lens of
about 4 inches diameter when necessary. Many rock-pools have
projecting ledges draped with fucus ; such are found to be espe-
cially prolific if well examined. The fucus should be turned
right back, so as to expose the sides it covered and the under
surface of the ledge, which are normally in deep shade. Sponges
growing underneath may be scraped off and examined for com-
mensal hydroids. If long, dark tunnels exist in the rock, the
arm should be pushed up and the upper surface of the rock felt
over with the hand for any adherent masses of sponge, etc.,
which may be broken off and examined. This is a distinctly
sporting method, as it gives the crab, when there, a chance to
get in first with his pincers. Bring him out and hold him under
water in the rock-pool while you go over him carefully with a
lens ; his carapace will probably recompense you for the pinched
finger. Shells, also, should be carefully examined. The only
time I ever took Podocoryne areolata was upon a shell found lying
at the bottom of a funnel-shaped rock-pool, and Professor
Allman had the same experience. Many species are so minute
as to defy detection by the ordinary methods of shore collecting
and are best obtained by taking small tufts of seaweeds and
looking over them at home with the compound microscope.
I have remarked previously that collecting is often very re-
munerative on shores strewn with large fucus-covered boulders.
Those who know Llandudno and Criccieth will recognise excellent
examples of such shores, and doubtless many similar exist round
the coast. The boulders near low-water mark yield the richer
harvest, and the underneath is the surface to work. Where
two of these huge boulders have fallen close together, so as to
form a miniature tunnel, the latter is sure to afford a prolific
hunting-ground. My method is to lie on my back and gradually
work into the tunnel, carrying a blunt knife and some fair-sized
bottles, or jars, of sea-water, The surface of the rock is chipped,
PRESERVATION OF THE HYDROIDA. 147
or scraped, where promising growth appears, and the gathering
dropped into the bottles, to be examined elsewhere and in a
more comfortable position. This is really an excellent method
of obtaining material.
Dredging is not likely to be undertaken by the occasional
collector unless he is a very enthusiastic one, and if undertaken
the individual will probably be in no need of advice from me, as
he will know more or less about it. To the beginner I would
say, choose a dredge of moderate size and confine dredging
operations to moderate depths, i.e. up to ten fathoms. If any
fishing industry is carried on where the collector happens to be,
he may get ample employment from a bucket of trawl refuse
obtained from one of the boats ; even the rejectamenta of
lobster-pots is a good hunting-ground. On an open sandy coast,
after a gale or heavy sea, deep-water specimens may be obtained
in excellent condition if the jetsam left by a receding tide is
carefully looked over. They should be promptly placed in bottles
of sea-water, to recover and expand their tentacles, and this
process may be aided by vigorously aerating the water by means
of a syringe.
Having collected the material, the less eventful work of pre-
paring it for the microscope follows as a matter of course, and
I believe I am doing beginners a service in urging upon them
the desirability of arranging for this to take place at the earliest
possible moment after collecting. Once the hydroids begin to
feel the effects of overcrowding and badly aerated water the
polyps withdraw into their calycles, and require a large expendi-
ture of time and patience to coax them to expand again. The
best results are undoubtedly got when the collector is in a
position to go straight from the shore to his microscope and deal
with the material collected. The polyps are then vigorous from
their normal environment, less intolerant of the narcotising
agent, and a considerable quantity of material can be dealt with
in a comparatively short time, as there is no tedious waiting
for the polyps to expand. My own method is to divide the
collection into two lots, separating the Gymnoblastea from the
Calyptoblastea, as the former can be best prepared by killing
without the intervention of a narcotic. The hydroids are placed
in watch-glasses (or better still small Petri dishes) with clean
fresh sea- water, and cleansed as far as can be without injuring
148 G. T. HARRIS ON THE COLLECTION AND
the polyps by gently brushing the polypary with a camel's hair
brush. They are allowed to recover from the shock, and then
a few drops of 1-per-cent. cocain hydrochlorate added to each
watch-glass and the glasses set gently aside until all the species
have been dealt with. When the polyps are fresh and vigorous
narcotisation is not a difficult process, nor one requiring extreme
care, but should the hydroids be left twenty-four hours or so
before dealing with them the process is likely to be not only
tedious but generally unsuccessful. When the polypites are
judged to be sufficiently narcotised to permit of killing the
tentacles should be pricked with a needle somewhat roughly, to
be quite certain that narcotisation is sufficient to prevent retrac-
tion of the tentacles. I learnt by experience that even when
insensibility was apparently well established, on the application
of the killing and fixing agent the polypites would withdraw at
least partially, perhaps wholly, into the calycles, so that it is
necessary to be quite sure that narcotisation is complete before
using the fixing fluid. The killing and fixing agent most con-
venient is undoubtedly osmic acid, either a plain 1-per-cent.
solution or combined with platinum chloride as in Hermann's
solution. I have tried many other solutions for this purpose,
but found none more suitable. The osmic-acid solution is sprayed
over the colony in the watch-glass with a pipette and allowed to
act for several minutes, when it is washed away by repeated
changes of clean fresh water, allowing the specimens to soak in
each wash water for some time. Finally they are given a
weak bath of hydrogen peroxide or potassium ferrocyanide, to
thoroughly eliminate the acid, and again well washed. This is
the procedure for Calyptoblastic hydroids, the Gymnoblastic
may have a little more cavalier treatment. If narcotisation is
attempted with them it has the effect of causing them to
gradually shorten the tentacles, and once that has taken place
they never extend them again while under the influence of the
narcotic. This being the case the best method is to kill them
suddenly with an energetic killing agent while fully expanded.
Some retraction of the tentacles may take place in the killing,
but to nothing like the extent that would happen if narcotisa-
tion were attempted. It is unfortunate that mono-bromide of
camphor is insoluble in sea-water, as I am convinced, from the
admirable results it gives with Cordylophora and Hydra, that
PRESERVATION OF THE HYDROIDA. 149
it would form an excellent narcotiser for this division. Lang's
fluid is a good killing agent for the Gymnoblastea, and, of course,
assists staining if carmine is used. Picric acid also answers well ;
and osmic acid or Hermann's solution if the specimens are not
too large, otherwise I have found the killing occupy sufficient
time to permit of considerable contraction.
Undoubtedly the great difficulty in preparing hydroids for the
microscope lies in getting clean mounts — that is, supposing clean
mounts are desired — and this difficulty becomes augmented with
material from between tide-marks. The polyparies are generally
encrusted and overgrown with an olla podrida of marine life, so
that the mount really becomes a compound object. To me
this is anything but a drawback, providing, of course, that no
essential part of the hydroid is masked. On some shores, how-
ever, the amount of material collected is out of all proportion to
its interest, and it becomes necessary to subject it to a cleansing
process. This should be done before narcotising and killing the
hydroid, otherwise the tentacles are liable to be injured and
entangled. The polyps withdraw into their calycles during the
application of the brush, but soon recover from their fright when
placed in a glass of clean fresh water and allowed to rest quietly
for a time.
If staining and mounting fixed material are deferred until a
more convenient time, it has to be stored in some preservative
fluid ; formalin at once suggests itself, for which reason I
wish to utter a word of warning. Formalin is perfectly satis-
factory for objects that are to be mounted unstained, as they
will eventually find a permanent home in this medium, but
personally I have not been successful in staining material that has
been stored for some months in a 5-per-cent. solution of formalin.
This, of course, may be due to some error peculiar to myself, but
I would offer this warning to inexperienced workers. If time
and facilities allow I would strongly advise the beginner to stain
straight away, and if unable to mount, then store the stained
material in 70-per-cent. alcohol. Tailing this, I think it prefer-
able to store those hydroids destined for staining in 70-per-cent.
alcohol. In storing avoid the error of putting too many into one
tube ; small tubes with a few in each are very much better than
a heterogeneous collection of species in a large tube or bottle.
The microscopist will doubtless have his own pet stain or stains,
150 G. T. HARKIS ON THE COLLECTION AND
and as a good general stain is all that is required for systematic
work it does not much matter which is used. I have used
principally para-carmine, carmalum and haemalum of Mayer's
formulae; the last of which I prefer on account of its better
visual properties, also because it stains exceptionally well objects
that have been fixed with osmic acid. I may here mention that
haeniatoxylin has been regarded by some workers as a fugitive
stain ; why, I am unable to discover. I attempted to bleach
some slides that had been over-stained by exposing them for some
months in a window with a south aspect, and at the end of that
time withdrew them as hopelessly permanent. They should have
faded, according to all the authorities, but much to my disgust
they did not.
For unstained objects I use excavated slips, and a 2^-per-cent.
solution of formalin. A ring of old, fairly thick gold size is run
round the edge of the hollow and allowed to become nearly dry, at
least dry enough to retain the impression of a scratch made with
a needle. The selected portion of the hydroid colony is placed in
the cell, and 2|-per-cent. formalin solution added until a full cell
with a convex surface to the fluid is obtained. The cover-glass is
then placed in position, expelling the superfluous formalin. Under
a mounting microscope, with a strong blunt needle, the cover-
glass is pressed into intimate contact with the ring of gold size,
until it can be seen that no lacunae exist between it and the cover-
glass. The extraneous formalin is now removed and the slide
allowed to dry, when several rings of gold size may be applied.
Slides so prepared have attained the comparative antiquity of
sixteen or eighteen years without showing any deterioration.
As this paper has been prepared with the object of placing
practical information before those desirous of devoting some
attention to our hydroid fauna, it may not be considered alien to
the subject if I refer briefly to various localities of which I have
personal knowledge, from collecting more or less frequently in
them ; merely premising that my acquaintance with them as
collecting-grounds has been more by accident than design, and I
have no wish to suggest that they are any more desirable from
the collector's point of view than numbers of others unknown to
me. In North Wales my collecting-stations have been Llandudno,
Menai Straits, Criccieth and Barmouth. Llandudno and Criccieth
are excellent grounds. The rocks at I4andud.no under the Great
PRESERVATION OF THE HYJDROIDA. 151
Orme afford plenty of work at low tide, but rock-pools are
practically non-existent ; I have taken many good northern
species from the under-sides of the boulders strewn about.
Criccieth is a capital ground ; the rocks on the shore at the foot
of the Castle Hill repay the most ample attention, yielding many
and good species. A short distance from Criccieth are the Black
Rock caves, which are really a paradise for the shore collector,
but are only accessible at low tide. The Menai Straits, also, have
good collecting-spots on the rocks at the Suspension and Tubular
bridges, but the drawback to work thereabouts is the swiftness of
the tide, which makes boating difficult and risky unless accom-
panied by a local boatman. Pennington collected many species
between the two bridges. Staithes, in Yorkshire, has a good
shore for collecting, as the rock-pools are ample. Coming now to
Devonshire, with whose shores I have intimate acquaintance, we
reach ground made classic by the labours of Gosse, Hincks,
Allman, Kingsley, Montagu and many others. Ilfracombe, in
North Devon, has the advantage of clear rock-pools, in places an
almost vertical rise and fall of tide, and excellent boating and
dredging. As it has received its meed of praise at the hands of
such authorities as Hincks and Gosse, not to mention Lewes, it
may be considered sufficiently hall-marked. Torquay, Gosse's
home and hunting-ground par excellence, is indubitably an ideal
district ; I know no better. The collecting at the Corbon's Head
alone will occupy a long holiday, and the coast under Livermead,
Kingsley 's one-time residence, is honeycombed with charming
rock- pools full of hydroid life. At Brixham one gets in touch
with a tiawling district, and plenty of chances occur of going
over trawl refuse. In East Devon, from Exmouth to Sidmouth,
the naturalist has to set a watch on his lips, for the combination
of excellent rock-pools and cliffs of Keuper marl is more than the
average shore collector can bear unmurmuringly. At the same
time, the fauna of these rock-pools is both luxuriant and diversi-
fied ; and one has to remember that it was principally in East
Devon that Hincks collected both hydroids and Polyzoa.
I would conclude with an apology for the extremely elementary
nature of this paper. It is a mere account of personal methods,
offered to the inexperienced in the hope of smoothing away some
of those preliminary difficulties that appear to be " commensal "
with the early days of all new subjects.
152 g. t. harris on the collection and
Notes on Some Species of Hydroida, principally intended
for Purposes of Identification.
Clava multieomis.
The polypites in this species are scattered, not grouped as in
the next.
Clava squamata.
Polypites in groups, clustered, gonophores in dense clusters at
base of tentacles.
Clava cornea.
Clusters of polypites much smaller than in C. squamata, gono-
phores smaller and less densely clustered. The two species are
closely allied, and Dr. T. S. Wright considered cornea a variety
of squamata.
Podocoryne areolata.
Apparently a rare species, as Hincks only records it from three
localities. It is easily distinguished by the sessile gonophores
being borne on the chitinous expansion of the stolon.
Coryne vaginata.
The common species of the south coast, and may be recognised
principally by the cup-like membranous expansion of the polypary.
It is essentially a rock-pool species.
Coryne pusilla.
In this species the tentacles are " more truly whorled than in
any other form of Coryne " (T. H.). The polypites are linear in
shape, and "of about equal size from one extremity to the other "
(T. H.). The only specimen I have ever had was found in some
material sent from Marazion.
Eudendrium ramosum.
The height given for this species by Hincks is "about
6 inches," but it appears to become dwarfed as it nears a littoral
habitat.
Eudendrium insigne.
In the absence of gonophores the specific name can only be
given with considerable hesitation. Hincks states its habitat
PRESERVATION OF THE HYDROIDA. 153
"to be between tide marks on the south coast, and mentions
a circular groove near the base of the body as a means of
identification.
Perigonimus sessilis.
The only species with ringed coenosarc. The polyp not dilated
underneath the tentacles.
Bougainvillea muscus.
Allman distinguishes this species by its small, habit and the
fact that its stems consist of a single tube, instead of being
composed of several tubes coalesced into one. The records for
this species seem to be very scanty.
Clytia Johnstoni.
The pedicel in this species is usually ringed at the top and at
the bottom, being smooth in the middle portion. Some specimens
are, however, more or less ringed throughout.
Obelia geniculata.
This species is readily distinguished by the projections sup-
porting the ringed pedicels bearing the hydrotheca.
Campanularia neglecta.
The margin of the calycle in this species is crenulate. This
■can only be seen with difficulty, as it is so readily damaged.
Halecium Beanii.
It may be easily identified when bearing female capsules by
their distinctive shape and the short tubular orifice in the middle
of the capsule.
Sertularia filicula.
This hydroid varies in the position of the calvcles on the stem,
some being placed oppositely, and some more or less alternately.
It may be distinguished by the single erect calycle in the axils
of the branches. It is a deep-water species (20 fathoms), and
more especially a northern species. Hincks never met with it
in Devon or Cornwall, so its occurrence in rock-pools at Sidmouth
is somewhat noteworthy.
Jourx. Q. M. C, Series II.— No. 73. 11
154 G. T. HARRIS, COLLECTION AND PRESERVATION OF THE HYDROIDA_
Plumularia pirmata.
The Plumulariidae are somewhat difficult for the beginner to>
separate, owing to the superficial resemblance of one species with
another. The most -trustworthy means of separating the species
is by a careful observance of the nematophores and distances of
the calycles. In P. pinnata the nematophores are very minute,
and lack the pronounced calycle present in other species, and.
are one below each hydrotheca. The gonothecae also, when
present, help materially in distinguishing the various species.
In the present species they are ovate, with spinous projections
on the top.
Plumularia setacea.
It somewhat resembles the former species, but the nema-
tophores are very different, being of superior size and differing in
number. The gonothecae are quite different, being flask-shaped ;
their axillary position also is an aid to diagnosis.
Plumularia echinulata.
In this species the pinnae have an unmistakable arched form
which does not occur in the others. The nematophores are
smaller than in P. setacea, and one nearly always occurs in the
axils of the pinnae. The gonothecae, however, when present
readily determine the species.
Plumularia similis.
This appears to be very near the former species (P. echinulata),
but the gonothecae are totally dissimilar, being without the
spinous projections.
Plumularia halecoides.
A minute species, and easily overlooked, The polypites have-
been compared to an hour-glass in shape. The gonothecae are
transversely ribbed. Nematophores very minute and difficult to
detect.
[The above notes are intended for use with a series of slides
presented to the Cabinet by Mr. G. T. Harris.]
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 73, November 1913.
155
THE MINUTE STRUCTURE OF COSCINODISCUS ASTER.
OMPHALUS AND OF THE TWO SPECIES OF
PLEUROSIGMA, P. ANGULATUM AND P. BALTICUM
By T. A. O'Donohoe.
{Read May 28th, 1913.)
Plate 14.
In preparing this paper it was, at first, my intention to refer in
no way to the work of others, of which, in fact, I had very little
knowledge. It has, however, been pointed out to me that it is
desirable to mention previous researches, in order to enable the
reader to compare these more easily with my own. Happily
Mr. E. M. Nelson gives a brief summary of his work on the
valve of Pleurosigma in a note read at the Club on January
28th, 1913 (Journ. Q. M. C, vol xii., p. 98). This note is
therefore easily accessible to all my readers, and any further
reference to it by me would be unnecessary. I regret I cannot
so easily dispose of the observations of Mr. T. F. Smith, who
has for many years devoted much time and thought to the
structure of diatoms, and who has so recently as August 1911
and October 1912 contributed to Knowledge two papers on this
much-discussed subject, entitled " The True Structure of the
Diatom Valve." These papers contain very many photo-
micrographs, of which several are excellent. I very much
regret, however, that I cannot agree with what I must call
his heterodox views. In his own words, "The points desired to
be driven home in the present article are that diatom structure,
consists of neither beads nor perforations as commonly under-
stood" (page 291).
Speaking of Pleurosigma for mosum, he says: " It appears to
consist of a series of chains, as it w-ere, formed of short bars or
fibrils of silex, arranged lengthways on the valve. They run in
pairs, parallel, each pair having larger and narrower interspaces
between them in regular succession, and so placed that the larger
interspaces are set obliquely to the corresponding interspaces
between the other pairs both above and below." A few lines
farther on he tells us that " his theory is this, that what we see
in the Pleurosigma valve when sound is not the structure at
all, but simply a collection of focal images thrown from the other
156 T. a. o'donohoe on the minute
layer upon the one nearest the eye, just as a picture is thrown
from the optical lantern upon a canvas screen. The fibrils or
grating is the real structure, of which the texture is concealed,
•even as that of the canvas screen is concealed by the picture."
So much for this new theory. We can consider only a few of
its points. The figures given on page 289 are, we are told,
photomicrographs of the two separated membranes of a valve of
Pleurosigma angulatum. If two really good photographs were
taken of these two membranes at about 4,000 diameters, they
would, in my opinion, make an end of Mr. Smith's theory, but
instead of giving his readers two such images, which would be
extremely interesting and valuable, he gives them a great
number of outers ides and innersides which, he tells us, do not
show the structure at all, and are therefore of very little value.
Indeed, I may say for myself that I attach little or no value to
interpretations of fine diatomic structure other than those of
thoroughly separated single membranes. Of these only can we
speak with a fair degree of certainty.
Turning now to page 331, we find that Mr. Smith says : " Fig.
14 is from an innerside of another valve (of P. formosum), the
first ever seen and taken, showing the fracture through un-
doubted perforations," and Mr. Nelson, being called to his aid,
testifies that " Mr. Smith has found this fracture, had shown it
to him, and that at any rate the fracture did run through the
holes." So, too, Mr. Smith cites the testimony of Dr. Dallinger,
who says : " In Plate I. fig. 1 (Carpenter on the Microscope) we
have a photograph of his showing the inside of a valve of
Pleurosigma angulatum magnified 1,750 diameters, exhibiting
the " postage-stamp fracture." The postage-stamp fracture is,
as everybody knows, a fracture through the holes, so that we
have these two great authorities testifying to the fact that these
photographs of Mr. Smith show fractures through holes, or, as
Mr. Smith calls them, undoubted perforations. His theory being
that there are neither holes nor beads in the valve of a
Pleurosigma, does he now repudiate these photographs and
these testimonies'? He speaks of his fibrils forming interspaces,
chains and gratings, and it would be interesting to have his
definitions of these terms. Can there be chains or gratings
without intervening spaces, i.e. holes or perforations ?
Fig. 18, page 333, " The innerside of Pleurosigma angulatum
X 3,770," by no means a sharp image, shows, nevertheless, holes
galore to any one who is not blind or unwilling to see them.
STRUCTURE OF C0SC1N0DISCUS AsTEROMPHALUS, ETC. 157
Mr. Smith's second paper (October 1912) I cannot touch : the
exigencies of space forbid.
I am indebted to two members of the Club for the loan of two
slides — realgar mounts — which have enabled me to study the
minute structure of Pleurosigma angulatum and Pleurosigma
balticiua. Having taken several photographs from a slide lent
me by my friend Mr. Bruce Capell, I showed some of them to
our Secretary and Editor, and the latter informed me that
Mr. Nelson was engaged more or less on the same subject, and
suggested that I should send him copies of my photographs.
This suggestion I fell in with the more readily inasmuch as it
would give me the benefit of any adverse criticism which Mr.
Nelson might feel himself called upon to make. To elicit this I
wrote on the back of each a brief interpretation of the structure,
and in one case in which I was much puzzled I placed a note of
interrogation. With his usual kindness and urbanity, Mr. Nelson
gave the desired information, but instead of adverse criticism he
sent me two slides of great historic as well as intrinsic value.
From these I have been enabled to make some photographs
which confirm the results already obtained from the slide belong-
ing to Mr. Bruce Capell.
Coming now to my immediate subject, my readers are, no
doubt, aware that Dr. Van Heurck tells us that a diatom valve
consists of two membranes and of an intermediate laver which he
calls a septum, and that it is this latter layer which contains the
cavities or perforations. In my opinion this definition connotes
at once too much and too little : too much by giving the valve
three layers, and too little by confining the cavities to the septum
only. In the three valves which we are about to consider, I find
only two layers or membranes, each of which has its own perfora-
tions. We will, in the first place, consider the structure of
C oscinodiscus asteromphalus. The photographs are taken from
some of my own mounts in styrax. Of course I am aware that
this valve was very ably and fully treated recently elsewhere by
Dr. Butcher (Journ. R. M. S. 1911, p. 722), but my chief object
in bringing it before you now is to determine, if we can, which is
the correct image, the black dot or the white dot. [Here Mr.
O'Donohoe illustrated his remarks by photographs projected on
the screen.] The black- and white-dot images now thrown on the
screen have been taken direct at a magnification of 4,000
diameters, and to my mind it seems perfectly obvious that two
images so utterly unlike one another cannot both be correct
158 T. a. o'donohoe on the minute
representations of the same structure. The next two slides show
the inner membrane projecting beyond the outer one, and on
examining the edge of the fracture it becomes at once evident
that what is called the eye-spot is a comparatively large
perforation. This membrane also shows considerable thickness.
I have been able to find a small fragment in which the outer
membrane projects a little beyond the inner layer. This is seen
by the fact that the silex of the projecting part appears white.
It should now be noted that this white silex is sharply defined at
the edge, that this edge shows hardly any thickness, and that the
perforations are represented by black dots. The next image has
been obtained by making no other alteration than that of raising
the objective until the white dots appeared. On examining this
image we find the white silex has become black, and the edge of
the fracture which was so well defined in the black-dot picture is
now so blurred and fogged as to have become invisible. We have
next two fragments of Pleurosigma angulatum in juxtaposition,
showing respectively the black and white dots. The black dot
image gives the "postage-stamp" fracture well defined in white
silex, whereas the broken edge in the other fragment is black,
out of focus and blurred. We are therefore justified, I think,
in relegating the white-dot images of diatom structure to the
abode of Mr. Nelson's ghosts. Here, methinks, I hear the tyro
in microscopy cry out, " If that be so, why do we meet with
so many white-dot images in the books which are written for
our guidance ? " I prefer to let the writers of these books
answer for themselves. Mr. Pringle, in Practical Photomicro-
graphy, 1890, page 173, writes: "In spite of all these details,
A. pellucida is child's play to photograph in comparison with
such tests as Pleurosigma angulatum, Surirella gemma and
Navicula rhomboides by axial light and to show ' black dots.
Pleurosigma angulatum in white areoles, or Navicula rhomboides
in squares, with a special disc in the condenser, is infinitely
easier than the same in black dots."
Let us turn now to Plates III. and IV. of Dr. Spitta's Photo-
micrography (1899). What do we find? White-dot images of
all his diatomic tests. Not one black-dot image ! He has, no
doubt, some good reason for this, and turning to page 138 we
find it. Writing about the photography of Pleurosigma
angulatum, Dr. Spitta says : " It has two principal planes of
focus, and much difference of opinion exists as to which is the
correct one. The last picture taken by Dr. Van Heurck with
STRUCTURE OF COSCINODISCUS ASTEROMPHALUS, ETC. 159
the new Zeiss N.A. 1*6 objective, and the attendant para-
phernalia, seems to show that after all the black dot is more
^correct than the white one. As before stated, the white one
is the easiest to photograph, for the black dot seems never to
be sufficiently defined to look as sharp as we should like it."
For the sake of the aforesaid tyro I will here quote a little
advice which Mr. Nelson gave me eight years ago (I began
photomicrography very late in life) on the white dot. Among
several black-dot photographs which I sent him, and which he
was kind enough to praise, there was a white-dot Isthmia
nervosa of which he said : ': I think the Isthmia would be better
with black-dot focus ; this white-dot focus is an out-of -focus
ghost. It is much easier to get than a correct picture, and on
that account it seems to be a favourite with some photo-
graphers ; but any one really interested in the work should aim
At something higher. Of course, with very fine structures, a
white dot is all that can be obtained with our present lenses."
I thought then, and still think, that this was the kind of
mentor who would always command and receive the highest
respect.
We come now to Pleurosigma angulatum, of which a black-dot
image x 3,700 is thrown on the screen. The next picture on the
screen shows a fractured valve which has been denuded of a part
of its outer membrane. The next image shows this outer mem-
brane x 2,000 broken up into fragments so minute that the
particles of silex have in some instances only one, two, three or
four holes shown as black round dots ; this outer membrane is so
thin that the silex is almost invisible, and in this respect differs
very much from the inner membrane, whose image x 2,000 is
now thrown on the screen. I do not, however, discern any
difference between the holes in the two membranes.
Finally, we have to consider the structure of Pleurosigma
balticum. This, because of its convexity and thickness, is difficult
to photograph, and yet more difficult to understand. I am
illustrating its structure by showing you fifteen different photo-
graphs, each of which I must describe very briefly ; but before
doing so, let me define the word " fibril " : a fine filament of silex
which contains holes in a row like a string of beads ; it may
be long or short. This definition differs altogether from that
which Mr. T. F. Smith gives to the same word.
The first slide shows the ordinary valve with Van Heurck's
■canaliculi x 1,500.
160 T. A. O'DONOHOE ON COSCINOD1SCUS ASTEROMPHALUS, ETC.
The second slide shows the round black clots of the inner
membrane near the nodule, where the outer membrane has been
rubbed off (PI. 14, fig. 1). The third slide shows an impression
of the greater part of a valve caused by the adhesion of the outer
membrane to the slip.
The fourth slide shows a similar adhesion to the cover-glass,
as well as the valve from which the outer membrane was torn.
The fifth shows the same x 1,000.
The sixth slide shows fine hair-like bent fibrils breaking away
from the valve.
The seventh shows a part of the same valve x 2,000, on which
four fibrils of the inner membrane are visible.
The eighth is an image which puzzled me, and Mr. Nelson
kindly explained it thus : " This shows an upper bar crossing a
hole. It also shows the transverse girder work wonderfully
clearly" (PI. 14, fig. 2). The ninth slide shows the structure of
the inner membrane to be similar to the last, but this and the
three next following photographs were taken from Mr. Nelson's
slide.
The tenth shows the outer membrane breaking up into fibrils,
and sometimes even into isolated clots (PI. 14, fig. 3).
The eleventh and twelfth show continuations of the tenth.
The thirteenth shows the structure of the fibrils very well (PI. 14,
fig. 4). The fourteenth and fifteenth show the kind of structure
which is incorrectly taken for squares, but a glance at one of
the single fibrils causes the optical illusion to vanish.
In Pleurosigma balticum the fibrils run parallel with the raphe,
whereas in Pleurosigma angtdatum they seem to run obliquely to
the raphe, and this, it seems to me, is the chief difference in the
minute structure of the two valves.
Description of Plate 14.
Fig. 1. P. balticum, X 1,750. Showing the structure of the
inner membrane when the outer has been rubbed off.
,, 2. P. balticum, x 2,000. Inner membrane, showing the
holes crossed by very fine bars of silex.
„ 3. P. balticum, x 2,000. Fibrils, photographed from Mr.
Nelson's slide.
,, 4. P. balticum, x 1,250. Fibrils.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 73, November 1912.
Journ. Q.M.C.
Ser. 2, Vol. XII , PI. 14
1
ill
ll III
will
I
.Hi!
•!
Pliilli
.:
I
it:
!!i
♦
t
III*
Fig. 1.
Fig. 3.
Fig-.
Fig. 2.
Photomicrogr. T. A. OD.
Structure of Pleurosigma balticum.
1G1
LAGENAE OF THE SOUTH-WEST PACIFIC OCEAN..
(SUPPLEMENTARY PAPER.)
By Henry Sidebottom.
{Read June 24/7/, 1913.)
Plates 15-18.
INTRODUCTION.
The Lagenae dealt with in this supplementary paper were-
arranged by the late Mr. Thornhill on nine slides, each of which
is divided into one hundred squares. Nearly every square is
occupied, with the exception of some on the last slide. The
number of specimens exceeds twelve thousand. In the material
for mv first paper the number of specimens of Lagenae exceeded
six thousand, thus making a grand total of over eighteen thousand.
For reasons stated in my former Introduction, it has not always
been possible to give the locality at which specimens were found.
The series dealt with now is on three sets of slides, Nos. 1-4 A
being Penguin gatherings, Nos. 1-3 b Penguin and Dart gatherings
combined and Nos. 1,2 c those on which Mr. Thornhill had just
begun to bring together specimens arranged according to a system
he had hoped to carry out.
The specimens of Lagenae on the three sets of slides were not
arranged in sequence with each other, so that the work has
proved more laborious than that of my first report.
The division of the keel, which occurs in a good many tests
and in more than one species, adds to the difficulty of identifica-
tion, and it is easy to be misled by it. The same may be said
of some of the markings on the faces of the test, which have
hitherto been considered as specific characters.
Again I must acknowledge the kindness of Mr. Millett, whose
advice I have always found most valuable and freely given. My
thanks are due to Mr. Wright, of Belfast, to Prof. Hickson,
of the University of Manchester, for kind assistance, and also
to Mr. Earland for bringing these papers before the Quekett
Microscopical Club and examining specimens for me in order to-
162 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
find out the nature of certain markings. Lastly, as regards the
text, I wish to acknowledge my indebtedness to my wife for her
assistance in rendering my descriptions more concise.
H.M.S. " Penguin." S.W. Pacific. 1897.
No.
Statioi
1.
939.
2.
940.
3.
941.
4.
943.
5.
945.
6.
947.
7.
949.
8.
952.
9.
954.
10.
955.
11.
956.
23.
f 2]
U7i
Lat. & Long.
f 18-29' S.
\ 178-38' E.
/ 18-57' S.
U 79-04'
/ 18-43'
U 78-51'
/ 19-21'
(.179-30'
21-47'
179-25'
/ 22-49'
\ 179-20'
/ 23-44'
\ 179-09'
/ 25-52'
\ 178-47' E.
f 26-57' 8.
1 178-35'
f 27-46'
\ 178-29'
/ 29-17'
i 177-17'
E.
8.
E.
S.
E.
S.
E.
S.
E.
S.
E.
S.
E.
S.
E.
8.
E.
H.M.S. "Pen
No. Station.
4.
24.
12.
18.
21.
24.
25.
27.
Lat.
r 33-
\157-
r 33-
\158-
/ 33-
U60-
f 33-
\161-
/ 33-
\162-
f 33
(163
/ 33-
V163-
f 33-
U64
/ 33-
\164
f 34
\165-
& Long.
53' S.
29' E.
50' 8.
47' E.
48' 8.
2' E.
56' S.
13' E.
56' 7"
S
33'
E
56' 6"
S
20'
E
57' 8.
•56' E.
58' S.
•37' E.
■58' 5"
S
•55'
E
0' 6"
S
37'
E
GUIN.
Fms.
2,578.
2,338.
1.190.
98S.
498.
575.
603.
1,073.
1,653.
1.676.
Fms.
No.
1,122.
12.
1,092.
13.
1,360.
14.
1,420.
15.
2,043.
16.
1,948.
17.
1,903.
18.
2,183.
19.
2,318.
20.
1,803.
21.
2,050.
22.
Station.
959.
961.
964.
974.
975.
976.
986.
987.
996.
998.
1,003.
Lat. & Long.
f 31-39' S.
\ 176-49' E.
/ 33-00' 8.
\176-16' E.
/ 34-52' 8.
(175-34' E.
f 35-01' S.
\171-37' E.
f 35-23' S.
1 170-34' E.
/ 36-09' S.
^ 169-20' E.
f 36-30' S.
\168-11' E.
f 37-10' S.
1 166-30' E.
/ 37-47' S.
\ 164-40' E.
f 38-24' S.
1 163-15' E.
/ 4305' 8.
(148-39' E.
S.W. Pacific. 1898.
No.
25. 1
Station.
35.
41.
44.
75.
26.
I
27.
28.
83.
85.
86.
87.
Lat. & Long.
/ 34-19' 8.
\168-6' E.
/ 34-20' S.
\ 168-28' E.
/ 34-22' 8.
\17019' E.
f 36-21' 8.
\176-44' E.
f 36-3' S.
\ 17855' E.
/ 34-33' S.
\. 178-15' W.
f 32-56' S.
\ 176-49' W.
S.
w.
/ 31-28' S.
{ 171-5' W.
/ 3216'
\175-54'
Fms.
2,210.
2,086.
917.
796.
994.
1,298.
1,207.
822.
735.
2,182.
1,611.
Fms.
828.
1,191.
979.
832.
1,389.
4,278.
3,360.
3,220.
3,100.
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 163
No"
Station
29.
93.
90.
^in
94.
ou.-
95.
96.
31.
98.
32.
143.
No.
37.
38.
39.
40.
Station.
140.
70.
181.
182.
188.
191.
192.
393.
429.
480.
Lat. & Long.
Fins.
f 26-38' s.
\17417' W.
2,420.
f 2917' S.
\ 175-11' W.
3,105.
/ 25-53' S.
U"46' W.
2,775.
f 23-24' S.
\ 173-40' W.
3,205.
f 22-14' S.
1 17329' W.
3,420.
/ 21-8' S.
\ 174-7' W.
2,115.
f 23-15' 8.
\175-32' E.
2,351.
1
H.M.S. "
Penguin
Lat. & Long.
Fms.
f 10-57' S.
\162-21' E.
508.
f 23-17' 8.
\ 154-33' E.
470.
/ 11-42' 8.
U75-51' W.
2,335.
f 11-09' 8.
\ 175 -36' W.
1,992.
f 9-41' S.
\ 174-37' W.
2,290.
/ 8-57' 8.
V 174-03' W.
2,606.
f 8-36' S.
\ 173-51' W.
2,712.
/ 3-51' N.
\ 164-13' W.
2,330.
/ 4-55' N.
\ 160-54' W.
1,701.
/ 5-10' N.
\ 160-15' W.
2,033.
No. Station.
f
33.
34.
35.
36.
14S.
149.
151.
156.
157.
167.
169.
172.
Lat. <fc Long.
f 261' 8.
\ 172-56' E.
f 26-38' 8.
\172-26' E.
/ 27-55' 8.
\171-22' E.
f 29-35' 8.
\ 168-51' E.
f 29-42' 8.
\ 168-51'
/ 30-29'
\ 166-16'
f 30-57'
\ 160-52'
T 31-18'
\ 163-46'
E.
8.
E.
8.
E.
8.
E.
S.W. Pacific.
No.
40.
41.x
Station.
482.
487.
488.
498.
499.
502.
503.
505.
506.
Lat. & Long.
/ 6-15' N.
\ 160-36' W.
/ 7-25' N.
\ 160-59' W.
f 7-47' N.
\ 160-45' W.
/ 8-47' X.
\ 159-45' W.
f 904' N.
\ 159-32' W.
/ 9-43' N.
\ 159-07' W.
f 1004' N.
1 158-53' W.
f 10-43' N.
\ 158-30' W.
/ 11-01' N.
X 158-21' W.
Fms.
2,428.
2,070.
1,632.
1,269.
1,446.
1,819.
1,557.
1,010.
Fms.
1,861.
2,501.
2,573.
2,588.
2,579.
2,758.
2,800.
2,938.
2,863.
Ko. Station.
f
No date
42.
Lat. k. Long.
2415' 8.
E.
S.
E.
/ 24-36' 8.
\15332' E.
/ 24- 1
\153-1
/ 24-34'
\ 153-32'
H.M.S. "Dart."
Fms.
328.
478.
392.
No. Station. Lat. <fc Long.
Fms
d, / 19. f 29-22' S.
^■\(14.5.97.)\153-51' E.
465
44.{(16.1.97.){1^; £
481
164 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
Family LAGENIDAE.
Sub-family Lageninae.
Lagena Walker and Boys.
Lagena globosa Montagu sp. (PI. 15, figs. 1-3).
Serpula (Lagena) laevis globosa Walker and Boys, 1784, Test. Min.r
p. 3, pi. 1, fig. 8.
Vermiculum globosam Montagu, 1803, Test. Brit., p. 523.
Very numerous and of varying size and shape. The orifice
and internal tube are subject to great variation. — Locality :
Many .stations.
PL 15, fig. 1. The orifice is small and somewhat hooded, and
the test often inclined to be apiculate. — Locality : Many stations.
Rare.
PI. 15, fig. 2. An elongate variety. — Locality: Uncertain.
Only one found.
PI. 15, fig. 3. An interesting variation, the body of the test
being partly clear and partly opaque. The curiously produced,,
flattened mouth, which appears to be divided or pinched in at the
centre, points to its being allied to the one figured + PI. 14, fig. 2.*
The entosolenian tube is absent. — t Locality : Nos. 21-26, 34, 38,
42, 44.
+ P1. 14, fig. 2. — Locality: Uncertain.
+ P1. 14, fig. 4. The slightly elongated form predominates. —
Locality : Many stations, including Nos. 6, 8 ; after No. 22 only
at one or two stations.
+ P1. 14, fig. 5. This compressed variety of the above is found
sparingly at a few stations, but tests that are much more com-
pressed, and pointed towards the aperture, are frequent.
Lagena globosa Montagu sp. single and bilocular form.
Lagena globosa Montagu sp. single and bilocular form, Sidebottom,
1912, Journ. Q. M. C, p. 380, pi. 14, figs. 7, 8, 9.
Locality : Many stations up to No. 19, also at Nos. 33, 43, 44.
* The "4*" denotes that the reference is to " Lagenae of the South-
West Pacific Ocean " (Journal Quekttt Microscopical Club, 1912, ser. 2,
vol. xi., pp. 375-434, pis. 14-21).
f The numbers throughout this paper refer to my charts on pp. 162, 163,
where will be found the official numbers of the stations, with other
particulars.
HENRY SIDEBOTTOM OX LAGENAE OF THE SOUTH-WEST PACIFIC. 165
Lagena globosa Montagu sp. var. maculata Sidebottom.
Lagena globosa Montagu sp. var. maculata, Sidebottom, 1912,
Journ. Q.M.C. p. 380, pi. 14, figs. 10, 11.
Locality : Nos. 5 9.
Lagena globosa Montagu sp. var. emaciata Reuss.
Lagena emaciata Reuss, 1862 (1863), p. 319, pi. 1, fig. 9.
Lagena globosa Montagu sp. var. emaciata (Reuss) Sidebottom,
1912, Journ. Q. M. G. p. 381, pi. 14, figs. 13-15.
Locality : Present at numerous stations throughout the series.
Lagena apiculata Reuss sp. (PI. 15, fig. 4).
Oolina apiculata Reuss, 1851, p. 22, pi. 1, fig. 1.
Lagena apiculata Reuss, 1862 (1863), p. 318, pi. 1, figs. 1, 4-8,
10, 11.
PI. 15, fig. 4. — A large, solitary specimen. — Locality : No. 15.
+ P1. 14, fig. 16. Always rare. — Locality : At Nos. 24, 43, and
a, few other stations.
"J" PI. 14, figs. 17, 18. Found at many stations. — Locality:
Chiefly at Nos. 2, 24, 42, 44.
*P1. 14, figs. 19, 20. The tube in this variation is very
delicate, and often lies broken inside the test. — Locality: Occurs
at very many stations.
Lagena apiculata Reuss sp. var. punctulata Sidebottom.
Lagena apiculata Reuss sp. var. punctulata Sidebottom, 1912,
Journ. Q.M. C, p. 382, pi. 14, figs. 21-23.
Locality : Nos. 3, 5-11, 41, 43.
Lagena longispina Brady (PI. 15, figs. 5, 6).
Lagena long ispina Brady, 1881, Quart. Journ. Micro. Sci., vol. xxi.,
N.S., p. 61.
Lagena longispina Brady, 1884, p. 454, pi. 56, figs. 33, 36 ; pi. 59,
figs. 13, 14.
As Brady states in the Challenger Report, this is simply a
variety of L. globosa. It is not unusual for L. globosa to have
the base of the test roughened or finely spinous. The larger of
166 HENRY S1DEB0TT0M ON LAGENAE OF THE SOUTH-WEST FACIFICL
the two specimens figured is so opaque that it is impossible to
say whether the entosolenian tube is present. — Locality : Nos. 5,,
7, 9, 39-41, 44.
Lagena ovum Ehrenberg sp.
Miliola ovum Ehrenberg, 1843, p. 166; — 1854, pi. 23, fig. 2;
pi. 27, fig. 1 ; pi. 29, fig. 45.
Locality : This unsatisfactory form occurs at many stations,
but is always rare. See remarks +p. 382.
Lagena botelliformis Brady (PL 15, figs. 7, 8).
Lagena botelliformis Brady, 1884, p. 454, pi. 56, tig. 6.
PI. 15, fig. 7. Only two specimens found. The orifice is phia-
line, and there is a short internal tube. — Locality : No. 44.
PL 15, fig. 8. This is a very fine example in the apiculate-
condition. See also +PL 14, fig. 24. — Locality: No. 12.
+ P1. 14, figs. 24, 25. — Locality; Many stations.
**"PL 14, figs. 26-28. — Locality: Stations uncertain.
Lagena laevis Montagu sp. (PL 15, figs. 9, 10).
Serpula (Lagena) laevis ovalis Walker and Boys, 1784, p. 3, pi. 1,.
fig. 9.
Lagena laevis (Walker and Jacob) Williamson, 1848, p. 12, pi. 1,
figs. 1, 2.
L, laevis occurs frequently in these gatherings, and the form
of the test, the decoration of the neck and the position of the-
internal tube varies. Some are apiculate. In a few instances
there is an entosolenian tube situated at the base. — Locality .-
Many stations.
PL 15, fig. 9. The tests are semi-opaque, the short neck is-
decorated and the internal tube straight. In several instances
fine spines project at the base. — Locality : Nos. 1, 2, 3, and one-
or two others.
PL 15, fig. 10. This appears to be a smaller variety of the-
above. The tests are too opaque for me to make out whether
the entosolenian tube is present. Some are apiculate and may-
be L. laevis var. distoma Silvestri. — Locality : At a good many
stations throughout the series.
HENRY SIDEBOTTOM ON LAGEXAE OF THE SOUTH-WEST PACIFIC. 167
Lagena laevis Montagu sp. var. distoma Silvestri.
Lagena laevis (Montagu) Silvestri, 1900, p. 244, pi. 6, figs. 74, 75.
Examples are rare, but they occur at a fair number of stations..
—Locality : Chiefly at Nos. 1, 6, 11, 15, 17, 22, 42-44. .
Lagena gracillima Seguenza sp.
Amphorina gracilis Costa, 1856, p. 121, p. 11, fig. 11.
Am ph or ina gracillima Seguenza, 1862, p. 51, pi. 1, fig. 37.
Eight specimens occur which are all curved. — Locality : No. 44.
Besides these specimens, only two or three others were found. —
Locality : Uncertain.
Lagena elongata Ehrenberg sp.
Miliola elongata Ehrenberg, 1854, pi. 25, 1a, fig. 1.
I do not think these can be separated from L. gracillima
Seguenza sp., as they appear to pass insensibly from one form to
the other. Seven specimens occur, also two or three doubtful
examples. — Locality : Six at No. 43, and one at No. 2.
Lagena aspera Keuss (PI. 15, figs. 11-13).
Lagena aspera Eeuss, 1861, p. 305, pi. 1, fig. 5.
Pi. 15, fig. 11. This is in good condition, except that the neck
is broken. The protuberances, which are arranged in lines, are,
I think, tubular. — Locality : No. 17.
On another square are two smaller specimens, with very small
protuberances ; these also have the neck fractured. They appear
to be a weak form of the above. — Locality : Uncertain.
PI. 15, £g. 12. Two specimens only occur ; the one figured is in
a very opaque condition, the other is clear but much smaller. —
Locality : Nos. 1, 22.
PI. 15, fig. 13. Three specimens found, the neck being bent to
one side in each case. It is not unlikely that future investigation
will reveal a connection between these forms and L. striatopunctata.
—Locality : No. 43.
There are also two oval tests, which have the protuberances,
and the lines in which they are arranged, farther apart. The
protuberances are very minute. — Locality : No. 10.
168 HENRY S1DEB0TT0M ON LAGENAE OF THE SOUTH-WEST PACIFIC.
Lagena rudis Reuss (PI. 15, fig. 14).
Lagena rudis Reuss, 1862 (1863), vol. 46, p. 336, pi. 6, fig. 82.
A single example. The test is opaque and of a faint silvery-
yellow colour. — Locality : No. 24.
Lagena ampulla-distoma Rymer Jones.
Lagena vulgaris var. ampulla-distoma Rymer Jones, 1872, p. 63,
pi. 19, fig. 52. See also + p. 384.
Locality : Nos. 1, 2, 3, 8, 19, 22, 24, 42, 43.
Mr. Millett, 1901, p. 6, mentions two other localities for this
species, besides the Malay Archipelago ; it may therefore be worth
while to state that I have since recorded it from the coast of
Delos and Palermo.
Lagena hispida Reuss (PI. 15, fig. 15).
Sphaerulae hispidae Soldani, 1798, p. 53, pi. 17, v, x.
Lagena hispida Reuss, 1858, p. 434.
Lagena hispida Reuss, 1862 (1863), p. 335, pi. 6, figs. 77-79.
In one form or another this is found at nearly all the stations.
There is great variation in size, and shape of the tests, and many
of the small ones have a long entosolenian tube at the opposite
end from the neck, so that it is difficult in some cases to say which
is the right end up. If turned one way, they might be treated as
apiculate forms.
PI. 15, fig. 15. The orifice is circular and sunk in a depression.
The oral end of the test is surrounded by a series of short spines.
A solitary example. Locality : No. 24.
* PI. 15, fig. 1. Ten specimens occur. — Locality : Nos. 5, 6, 8,
and a single example at either Nos. 41 or 42.
Lagena hispida Reuss, compressed form.
+ P1. 15, fig. 2.— Locality: Nos. 1-3, 5-7, 10, 24, 33, 34, 36,
38 40, 42.
Lagena hispida Reuss var. tubulata Sidebottom (PI. 15, fig. 16).
Lagena hispida Reuss var. tubulata Sidebottom, 1912, Joum.
Q. M. C, p. 385, pi. 15, figs. 3-5.
PI. 15, fig. 16. Nearly all the smaller tests have their necks
broken, and a few are very large, as can be judged from the
HENRY SIDEBOTTOM OX LAGENAE OF THE SOUTH-WEST PACIFIC. 169
drawing. The largest specimens have the body much clogged by
exogenous shell-growth, or debris, through which small spines
often project. — Locality : Nos. 17, 19. 24. 25, 35. 36. Always rare.
+ P1. 15, fig. 5. This variation, which is much more delicate in
every way. is found at many stations. — Locality: Xos. 1-11. 24,
25. 33, 35, 36. 39.
Lagena striata d'Orbigny sp. (PL 15. fig. 17).
Oolina striata d'Orbigny, 1839, p. 21, pi. 5, fig. 12.
Many examples at numerous stations. They vary remarkably
both in size and decoration. Many are apiculate. -f- See remark-.
p. 386.
PI. 15. fig. 17. In this, the fine costae project at the base. The
neck is bent to one side, the body of the test is also slightly
■curved. On a square by themselves are fifteen tests which have
the contour of L. clavata, with the point at which the test begins
to narrow towards the base sharply angular. Only two are
marked on the chart. Locality : Nos. 1, 3-5. 7. 8. 12. 17. 21, 24,
34. 39. 40.
Lagena (Amphorina) Lyellii Seguenza sp. is found frequently.
This form may be treated either as L. striata, or L. sulcata in an
apiculate condition.
* PI. 15. fig. 6. Twenty-three specimens are on the slide. —
Locality : Nos. 2. 3. 4.
* PI. 15, fig. 8. Fourteen fine examples occur, and a number
of smaller ones. Taking the whole series into account they pass
gradually into L. Lyellii Seguenza. — Locality; Nos: 2-12. 15, 17.
21, 24, 29, 31, 33, 34. 39. 40, 42, 43.
+ EL 15, fig. 9. Five typical tests are on the slide, but they
are mixed with others that are not typical, and so the exact
locality cannot be given with certainty. They were found, how-
ever, at one or two of the following stations. — Locality : ZSTos.
1, 5, 11, 13.
On another slide two examples are placed. — Locality : 2Sos.
23. 24.
Lagena striata d'Orbigny sp. var. tortilis Egger.
Lagena tortilis Egger, 1893, p. 329, pi. 10, figs. 61-63.
Two examples only. — Locality : Nos. 43. 44.
Journ. Q. M. C., Series II.— No. 73. 12
170 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC
Lagena striata d'Orbigny sp. var. striatotubulata Sidebottom.
Lagena striata d'Orbigny sp. var. striatotubulata Sidebottom,.
1912, Journ. Q. M. C., p. 387, pi. 15, figs. 11, 12.
This is well represented. A good many are more or less-
fractured, otherwise they are clean and fresh-looking. — Locality r
Nos. 4-12, 23, 24, 29, 33, 34, 39, 40.
Lagena distoma Parker and Jones.
Lagena laevis var. striata Parker and Jones, 1857, p. 27S, pi. 11,
fig. 24.
There is a single large specimen and it agrees with the
Challenger figure, pi. 58, fig. 11. — Locality : No. 2.
There are about twelve examples which have their sides slightly"
curved and parallel as in the type. — Locality : Uncertain.
Lagena lineata Williamson sp.
Entosolenia lineata Williamson, 1848, p. 18, pi. 2, fig. 18.
Many examples found. — Locality : Nos. 1, 2, 4, 5, 9, 10, 13-15,
17-20, 22, 24, 25, 36, 38, 42-44.
+ PI. 15, fig. 15. The variety with the costae curved occurs at
many stations.
Non-apiculate forms also are present.
Lagena variata Brady.
Lagena variata Brady, 1881, Quart. Journ. Micr. Sci., vol. 21,.
N.S., p. 61.
Lagena variata Brady, 1884, p. 461, pi. 61, fig. 1.
Only two typical examples. — Locality : Uncertain.
+ PL 15, fig. 13. The neck of the test is in many cases not so
long as in the figure referred to. — Locality : Nos. 14, 15, 17, 19,
22, 24, 25, 44.
Lagena costata Williamson sp. (PI. 15, figs. 18, 19).
Entosolenia costata Williamson, 1858, p. 9, pi. 1, fig. 18.
Occurs frequently, typical and otherwise, sometimes apiculate.
PL 15, fig. 18. This appears to be an elongate form with from.
HENRY SIDEBOTTOiM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 171
eight to ten costae. Entosolenian tube straight. — Locality :
Ud certain ; probably No. 22 and a few other stations.
PI. 15, fig. 19. These appear to be the same, but they have
only six costae, and occur more frequently. — .Nos. 15, 17-20, 23,
24, 29, 33-36.
+ P1. 15, fig. 16. — Locality: Many stations throughout the
whole series.
+ P1. 15, fig. 19.— Locality: No. 43.
Lagena acuticosta Reuss (PI. 15, fig. 20).
Lagena acuticosta Reuss, 1861, p. 305, pi. 1, fig. 4.
An unsatisfactory species, for it is linked closely with L. costata
on the one hand, and L. sulcata on the other. — Locality: Many
stations up to No. 22 ; afterwards extremely rare.
PI. 15, fig. 20. An odd specimen, probably a very weak form.
— Locality : Uncertain.
+ PI. 15, fig. 22. Tests similar or nearly so oc^ur, but they are
not so large. — Locality : Nos. 2, 7, and a few other stations.
Lagena melo d'Orbigny sp.
Oolina melo d'Orbigny, 1839, p. 20, pi. 5, fig. 9.
There are several fine typical examples and a few small ores
on the slide, but as they are mixed with other varieties the
locality cannot be determined.
The form with the cross-bars sunk, which is assigned by
Reuss to L. catenulata Williamson, 1862 (1833), pi. 6, fig. 75, is
also present.
Lagena hexagona Williamson sp. (PI. 15, figs. 21-23).
Entosolenia squamosa var. hexagona Williamson, 1848, p. 20, pi. 2,
fig. 23.
Very many beautiful specimens occur ; some are globular,
others pyriform, with and without necks. The depth and size of
the mesh var}7 greatly.
A few, w^hich I take to be L. geomeirica Reuss, 1862 (1863),
pi. 5, fig. 74, are exquisite, although the arrangement of their
cells is not always parallel. The cells are deep, and their sides
exceedingly delicate. Several have short necks. I have not
attempted to draw them, as I could not have produced the
172 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
desired effect. — Locality: Again the mixing of the varieties
prevents me from giving any definite information.
There are a few which appear to be the same as the one
figured by Brady in the Challenger Report, pi. 58, fig. 33, of
which the angles of the cells tend to become spinous, especially
at the base of the test. This peculiarity seems to be feebly indi-
cated in Brady's figure.
PI. 15, fig. 21. Several of this elegant form occur. — Locality :
Uncertain.
PI. 15, fig. 22. A globular variety.
PI. 15, fig. 23. A compressed variation of the above, but of
smaller size. These two forms are placed together on the slide.
— Locality ; Taking the two forms together they are marked
Nob. 2-5, 13, 17-20, 44.
Lagena squamosa Montagu sp.
Vermiculum sqtiamosum Montagu, 1803, Test. Brit. p. 526, pi. 14,
%. 2.
A few only are present. — Locality : Uncertain.
Lagena exsculpta Brady.
Lagenulina sulcata Terquem, 1876, Anim. sur la Plage de
Dunkerque, fasc. 2, p. 68, pi. 7, fig. 9.
Lagena exsculpta Brady, Quart. Journ. Micr. Sri., vol. xxi., N.S.,
p. 61.
Lagena exsculpta Brady, 1884, p. 467, pi. 58, fig. 1 ; pi. 61, fig. 5.
Five examples found, and they are compressed. Three of them
are in poor condition. These latter are not quite typical, as
the sculptui e becomes irregular at the base. — Locality : ISTos.
37, 39.
Lagena sulcata Walker and Jacob sp. (PI. 15, figs. 24, 25).
Serpula (Lagena) striata sulcata rotunda Walker and Boys, 1784,
p. 2, pi. 1, fig. 6.
Serpula (Lagena) sulcata Walker and Jacob, 1798, p. 634, pi. 14,
fig. 5.
This common foraminifer is well represented. In some the
body of the test is globular, and in others cylindrical. Apicu-
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 173
late forms also occur.— Locality : Nos. 4, 14, 15, 20, 24, 26, 38,
42-44, and a few others.
PI. 15, fig. 24. This is closely allied to L. alifera Beuss, 1870,
p 467.— Von Schlicht, 1870, pi. 3, figs. 15, 16, 21, 22.— Locality :
Nos. 3. 10, and two or three others.
PI. 15, fig. 25. This form, known as L. sulcata var. interrupta
Williamson, is hardly worthy of a varietal name, as it is not at
all uncommon for some of the costae or striae, both in L. sulcata
and L. striata, to be shorter than the others.
Lagena plumigera Brady (PI. 15, fig. 26).
Lagena plumigera Brady, 1881, Quart. Journ. Jficr. Sci., vol. 21,
N.S., p. 62.
Lagena plumigera Brady, 1884, p. 465, pi. 58, figs. 25, 27.
Two of the tests are similar to the one figured ; several others
are smaller and much damaged. — Locality : Nos. 1, 2, 43.
Lagena semilineata Wright (PI. 15, fig. 27).
Lagena semilineata Wright, 1884-5, App. 9, 1886, p. 320, pl. 26,
fig. 7.
Evidently a bold form of L. semilineata. — Locality: Three
examples at Station No. 2.
Lagena gracilis Williamson.
Lagena gracilis Williamson, 1848, p. 13, pl. 1, fig. 5..
This protean species is found at many stations throughout
the whole series. All the forms represented in the Challenger
Report, 1884, appear to be present. No line of demarcation can
be drawn between this species and apiculate forms of L. sulcata
and Z. striata ; they are also linked with L. distoma Parker and
Jones.
Lagena quinquelatera Brady.
Lagena quinquelatera Brady, 1881, Quart. Journ. Micr. Sci., vol.
21, N.S., p. 60.
Lagena quinquelatera Brady, 1884, p. 484, pl. 61, figs. 15, 16.
I take this to be a variety of L. gracilis.
Two specimens only. — Locality : No. 2.
174 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
Lagena semistriata Williamson.
Lagena striata var. /? semistriata Williamson, 1848, p. 14, pi. 1,
figs. 9, 10.
The great majority are small. Some have the neck bent to
one side and the body slightly curved. A few are cylindrical and
others have the contour of L. clavata d'Orbigny. — Locality : Nos.
1, 20-22, 29, 42-44.
Lagena crenata Parker and Jones var. (PI. 15, fig. 28).
Lagena crenata Parker and Jones, 1865, p. 420, pi. 18, fig. 4.
They are not typical, but I think they are best placed under
the above heading. The projecting parts at the base run partly
towards its centre as blades. The neck is not decorated. A few
of the examples are not so slim as the one figured, and have their
sides slightly convex. Thirteen specimens occur. I cannot give
all the stations at which they are found, but the following may
be indicated. Locality : 22, 43.
Lagena Thornhilli Sidebottom (PI. 15, fig. 29).
Lagena Thornhilli Sidebottom, 1912, Journ. Q.M.C., p. 390,
pi. 15, fig. 26.
They differ slightly from the one figured at the above reference,
for the upper parts of the wings are joined together so as to
form a hood, as shown in the figure. In one of the examples
the three cavities formed by the hood are blocked with exogenous
shell-growth.
Four examples occur. — Locality : 6, 8, 29.
Lagena stelligera Brady.
Lagena stelligera Brady, 1881, Quart. Journ. J/icr. Sci., vol. 21,
N.S., p. 60.
Lagena stelligera Brady, 1884, p. 466, pi. 57, figs. 35, 36.
A good many agree with Brady's Challenger figure, pi. 57,
fig. 35, but some are more slender, and several are very
minute.
See remarks, + pp. 391, 392.— Locality : Nos. 5, 14, 17-19, 21,
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 175
22, also Nos. 23, 24, 29, 32, 33, 35, 37, 39-41. From these latter
stations a few of the " nude " form were obtained.
* PL 16, fig. 1. In most of the specimens, some of the costae
-are more prominent than the others, but none of them are "inter-
rupted," as in the figure referred to. — Locality : 10, 22-24, 36, 39.
+ P1. 16, fig. 2. Numerous examples of this " nude " variety
are on the slides, some having very long, delicate necks. The
apiculate portion varies both in width and length. Two very
large tests were found, and except for the absence of the costae
they agree well with the Challenger figure, pi. 57, fig. 36. —
Locality : Nos. 2, 3, 5, 12, 19, 23, 24, 29, 32, 33, 35, 36, 38-40.
+ P1. 16, fig. 3.— Locality: Nos. 3-7, 9, 10, 13, 17, 23, 24, 26,
29, 33 35, 39, 40.
* PI. 16, fig. 4. Compressed. Nine examples found. — Locality:
Nos. 2, 24. Other stations uncertain.
Lagena stelligera Brady var. eccentrica Sidebottom (PI. 15,
fig. 30).
Lagena stelligera Brady var. eccentrica Sidebottom 1912, Journ.
Q. M. O., p. 392, pi. 16, figs. 5, 6.
PI. 15, fig. 30. On this specimen the ridge at the base is
scarcely perceptible. Two or three only found. — Locality: Un-
certain.
+ PI. 16, fig. 5. Not typically represented in these gatherings.
+ P1. 16, fig. 6. The examples generally have the ridge at the
base carried farther up the side of the test. — Locality : Nos. 11,
14, 37.
Lagena stelligera Brady var. eccentrica Sidebottom, com-
pressed form (PL 15, fig. 31).
This is the compressed form, and some of the specimens from
No. 43 are in fine condition. — Locality : Nos. 10, 13. 14, 19, 20-
43. Very rare, except at No. 43.
Lagena striatopunctata Parker and Jones.
Lagena sulcata var. striatoptmctata Parker and Jones, 1865,
p. 350, pi. 13, figs. 25-27.
Various forms are present. Some have the neck bent to one
.side, others have only a very short neck. The body of the test
176 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
also varies greatly, being occasionally almost globular. — Locality :
Nos. 1-3, 22, 24 26, 33, 34, 38, 42, 43.
Lagena striatopunctata Parker and Jones (?) var. complexa
Sidebottom.
Lagena striatopunctata Parker and Jones (?) var. complexa Side-
bottom, 1912, Journ. Q. M. C, p. 393, pi. 16, fig. 11.
"*" PL 16, fig. 11. None of the tests are in perfect condition,
all showing signs of the disintegration mentioned at the above
reference. — Locality : Nos. 7, 9, 24.
Lagena striatopunctata Parker and Jones var. inaequalis
Sidebottom.
Lagena striatopunctata Parker and Jones var. inaequalis Side-
bottom, 1912, Journ. Q. J/. C, p. 393, pi. 16, fig. 12.
Three tests are on the slide, but only two belong to this variety.
— Locality : Two of the following, Nos. 4, 10, 11.
Lagena striatopunctata Parker and Jones var. spiralis Brady.
Lagena spiralis Brady, 1884, p. 468, pi. 114, fig. 9.
Locality : Nos. 1-4, 22, 37, 38, 43, 44. Very rare except at
No. 1.
Lagena Fieldeniana Brady.
Lagena Fieldeniana Brady, 1878, Ann. Mag. Nat. Hist. (5) vol. 1.
p. 434, pi. 20, fig. 4.
Lagena Fieldeniana Brady, 1884, p. 469, pi. 58, figs. 38, 39.
A solitary, rather rotund example, of which the neck is broken
off short. — Locality : Uncertain.
Lagena desmophora Rymer Jones.
Lagena vulgaris var. desmophora Bymer Jones, 1872, p. 54,
pi. 19, figs. 23, 24.
The specimens are typical and in good condition. All are, or
have been, apiculate. The number of spines at the bate varies
from one to four. — Locality : Nos. 2, 5, 7-11, 13, 33, 40.
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 177
Lagena foveolata Reuss.
Lagena foveolata Reuss, 1862 (1863), p. 332, pi. 5, fig. 65.
Lagena No. 25, von Schlicht, 1870, p. 10, pi. 3, fig. 25.
Three or four only occur. The sculpture of the test is ex-
ceedingly fine. — Locality : No. 43, and one or two other stations
which are uncertain.
Lagena foveolata Eeuss var.
Lagena foveolata Reuss var. Sidebottom, 1912, Journ. Q. M. 0.r
p. 395, pi. 16, figs. 16, 17.
It is possible that further investigation may reveal this to be
an apiculate form of one of the variations of L. melo d'Orbigny
sp.— Locality .- Nos. 1, 2, 4, 6, 8, 10, 12, 14, 15, 17, 19, 21, 22,
24, 33, 36, 38, 40, 42-44.
Lagena foveolata Reuss var. spinipes Sidebottom.
Lagena foveolata R,3uss var. spinipes Sidebottom, 1912, Journ.
Q. M. 67., p. 396, pi. 16, figs. 18-20.
The tests are not in the best condition, and in some instances
the spines appear to be absent, or scarcely perceptible. The
rotund form does not occur. — Locality : Fifteen specimens at
at No. 2, three at No. 3, four at No. 4.
Lagena foveolata Reuss (?) var paradoxa Sidebottom (PI. 15,
fig. 32).
Lagena foveolata Reuss (?) var. paradoxa Sidebottom, 1912,
Journ. Q. M. C, p. 395, pi. 16, figs. 22, 23.
This is one of the commonest foraminifera in these gatherings.
The tests vary greatly in size and shape. — Locality : Nos. 1-22,
(except No. 17), 23-26, 29, 31, 33, 34-36, 39-41, 44.
Lagena lamellata Sidebottom.
r
Lagena lamellata Sidebottom, 1912, Journ. Q. M. C, p. 396,
pi. 16, figs. 24, 25.
I can only identify four tests. — Locality : Two occur at No. 43 i
the other station or stations are uncertain.
178 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
Lagena Hertwigiana Brady (PI. 15, fig. 33).
Lagena Hertwigiana Brady, 1881, Quart. Journ. Micr. Sci., vol. 21,
N.S., p. 62.
Lagena Hertwigiana Brady, 1884, p. 470, pi. 58, fig. 36.
The figure in my copy of the Challenger Report, pi. 58,
fig. 36, does not show the reticulation referred to in the description
of the species in the text, p. 470. In the three or four specimens
found in these soundings, the surface is roughened and the
perforations show very plainly. — Locality : Uncertain, with the
exception of No. 43.
Lagena Hertwigiana Brady var. undulata Sidebottom.
Lagena Hertwigiana Brady var. undulata Sidebottom, 1912,
Journ. Q. M. C, p. 397, pi. 16, figs. 26-28.
Many examples occur. — Locality : Nearly all the stations, but
chiefly Nos. 2, 7, 10, 17, 24, 34, 43.
Lagena pacifica Sidebottom.
Xagena pacijica Sidebottom, 1912, Journ. Q. M. C, p. 398, pi. 16 f
fig. 29.
Only two or three specimens found. — Locality : Uncertain.
Lagena splendida sp. nov. (PI. 16, fig?. 1-3).
I am quite at a loss how to describe this exquisite Lagena.
-adequately, and I am unable to draw it owing to the complexity
of its decoration, which is exceedingly minute. The test glistens
and most probably it has been apiculate. The neck is fractured.
There is a second specimen which I think is the same, but there
is a slight difference in its appearance which I am unable to
explain. It is apiculate. — Locality : Uncertain.
Note. — Not being able to get a satisfactory definition with my
microscope, I submitted the test to Mr. Earland for examination,
who had better means of lighting up the test than I had. His
observations were made with the assistance of a Zeiss vertical
illuminator and daylight instead of artificial light. He writes as
follows :
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 179
" The markings appear to be knife-edged costae, from one side
•of which triangular processes project at intervals. The apex of
the process barely touches the inner side of the adjoining co^ta.
. . . The triangular processes are Hush with the costae at their
base, but apparently sink away towards the apex, which is
probably but little raised above the wall of the test. The sunken
parts between the processes have a matt surface, whereas the
processes and costae are quite translucent."
I may say that my own examination of the test agrees to a
great extent with the above, but I think the edges of the costae
are waved (see PI. 16, fig. 3).
In a second communication Mr. Earland writes : " I succeeded
in getting a stereoscopic view of the shell under a ^ in. yesterday,
and it gave rather a fresh view of its structure. It seemed to be
covered with lines of pyramidal points in broken lines. Each
pyramid is a blunt spine."
I have not succeeded, however, in seeing these characters of the
test.
The figure (PI. 16, fig. 2) gives the effect of what I think I see
under the microscope, and it coincides to a great extent with
Mr. Earland's first description, though the details given in his
second communication do not appear to me to be necessarily
contradictory. I wish to acknowledge my sense of the trouble
Mr. Earland has taken in the matter.
Lagena spumosa Millett (PI. 16, fig. 4).
Lagena spumosa Millett, 1901, p. 9, pi. 1, fig. 9.
Most of the tests are slightly curved at the oral end, but the
■" bird's-clawlike " process is more slender than is indicated in
Mr. Millett's illustration. Several are more elongate than the
one figured.— Locality .• Frequent at No. 22 ; Nos. 24. 38, 40, 42,
43, and a few other stations.
Lagena spumosa Millett, var.
Lagena spumosa Millett var. Sidebottom, 1912, Journ. Q. 21. C,
p. 398, pi. 16, fig. 30.
It is curious that the aboral end of the test appears to have
teen slightly abraded, I think in all cases. — Locality : Nos. 4, 6,
7, 10, 11^ 13, 24, 25, 33, 35, 39, 40, 42, 43.
180 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
Lagena Chasteri Millett.
Lagena Chasteri Millett, 1901, p. 11, pi. 1, fig. 11.
See my remarks on the type-form + p. 398.
Lagena Chasteri Millett (var. ?).
Lagena Chasteri Millett (var. ?) Sidebottom. 1912, Journ..
Q.M.C., p. 398, pi. 1G, figs. 32-34.
Many occur, but I am quite unable to separate this variation
from the type, for the curious little " stopper " at the orifice is
never so pronounced as in Mr. Millett's figure, and is often
apparently absent. Taking the type-form and the variation to-
gether, for they are mixed on the slides, they occur as follows : —
Locality ; Nos. 1-4, 22, 34, 38, and frequently at Nos. 42-44.
Lagena pannosa Millett var.
Lagena pannosa Mille;t var. 1901, p. 11, pi. 1, fig. 14.
It is probable that two or three examples of this variation are^
present. — Locality : Uncertain.
Lagena intermedia Sidebottom.
Lagena intermedia Sidebottom, 1912, Journ. Q.M.C., p. 399,.
pi. 17, figs. 1-3.
Locality : Nos. 3, 11, 12, 23, 24, 29, 32, 39-41.
Lagena quadralata Brady.
Lagena quadralata Brady, 1881, Qua/rt. Journ. Micr. Sci., vol. xxL
(N.S.), p. 62.
Lagena quadralata Brady, 1884, p. 464, pi. 61, fig. 3.
In the Challenger Report Brady states that this Lagena is.
allied to the Lagena alifera of Reuss. I should prefer to con-
sider it as a variety of L. lagenoides Williamson var. tenuistriata
Bradv, for we know that this latter occurs in the trifacial
condition (see * PI. 19, fig. 5), and therefore it is not surprising
to find it with four equidistant keels ; also I have a good example
of Jj. lagenoides with five equidistant keels. The specimen found
is very small and not in the best condition. I think the wings
are tubular, but cannot be certain. On the same slide there-
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 181
are two examples with three keels, and two with five keels. —
Locality : One specimen at No. 1. Other stations uncertain.
Note. — One or two examples occur with four keels which are
not tubulated. These I should place as a variety of L. striata.
Lagena sp. in cert.
Lagena sp. incert. Sidebottom, 1912, Journ. Q. M. C, p. 399, pi. 17,
figs. 4, 5.
Locality : Three examples at No. 2, two at No. 24.
Lagena laevigata Reuss, sp. (PL 16, fig. 5).
Fissurina laevigata Reuss, 1850, p. 366, pi. 46, fig. 1.
Large and small examples of the type-form occur, but they are
not numerous. It is impossible to separate L. laevigata from
L. acuta, as the one passes insensibly into the other. Many other
examples are present in which the orifice is not central. Forms
ranging round Fissurina oblonga Reuss, 1862 (1863), pi. 7, fig. 89,
are frequent, and are found at many stations. A few specimens
occur that are circular in outline.
PI. 16, fig. 5. There are two sets of these and they vary a little.
Some have the appearance of being subcarinate, but this seems
to be caused by the test being clearer at its edge than at any other
part. Only two or three examples have the spines at the orifice
well developed, and most have a small wing at either side of the
neck. There is no internal tube. — Locality : Nos. 42-44.
Note. — These are not far removed from L. falcata Chaster,
1892, p. 6, pi. 1, fig. 7. On another square (locality uncertain)
there is one typical form, and there are also one or two others
that are carinate at the base, which seem to be intermediate
between L. falcata and Mr. Millett's figure of L. marginata var.
Millett, 1901, p. 497, pi. 8, fig. 21.
Lagena laevigata Reuss sp. var. virgulata Sidebottom (PI. 16,
fig. 6).
Lagena laevigata Reuss sp. var. virgulata Sidebottom, 1912,
Journ. Q. 21. C, p. 400, pi. 17, fig. 8.
PI. 16, fig. 6. A few fine examples placed amongst others which
are too opaque for me to be certain whether they belong to this
variation. — Locality : Uncertain.
182 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC^
Lagena laevigata Reuss sp. var.
Lagena laevigata Reuss sp. var. Sidebottom, 1912, Journ. Q. M. 0.T
p. 400, pi. 17, fig. 7.
+ P1. 17, fig. 7. Very rare.— Locality : Nos. 15, 34.
Lagena acuta Reuss sp. (PI. 16, fig. 7).
Fissurina acuta Reuss, 1862, p. 340, pi. 7, fig. 90, and F. apiculatar
p. 339, pi. 6, fig. 85.
Lagena acuta (including such as have only the slightest indica-
tion of the apiculate process) is found at almost all the localities..
The size and inflation of the tests, as well as their outlines, vary
greatly. — Two at No. 14.
Lagena acuta Reuss sp. var. (PI. 16, fig. 8).
The chief feature of this variety is the curious oval marking at-
the base, on both sides of the test. It is very rarely so clearly-
shown as in the drawing. The tests are opaque or nearly so, and
when the shell-substance becomes very dense the markings
disappear, but if damped some trace of them can be detected. —
Locality : Nos. 3-7, 9-11, 13 15, 29, 33, 34, 39, 40, 42, 44.
+ P1. 17, fig. 9. The mixing of this form wTith that of fig. 10'
prevents me from giving the exact localities, but it is evidently
rather rare. They correspond with the Fissurina apiculata Reuss,.
1862, p. 339, pi. 6, fig. 85.
Lagena acuta Reuss sp. var. virgulata Sidebottom.
Lagena acuta Reuss sp. var. virgulata Sidebottom, 1912, Journ..
Q.M. C, p. 401, pi. 17, fig. 10.
+ P1. 17, tig. 10. This appears to occur at nearly all the
stations up to No. 22, after which it is extremely rare.
Lagena acuta Reuss sp. var.
Lagena acuta Reuss sp. var. Sidebottom, 1912, Journ. Q. M. C^
p. 401, pi. 17, fig. 11.—
Locality : Nos. 3, 4, 6, 10, 11, 14, 24, 25, 34, 39.
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 183
Lagena lucida Williamson sp. (PI. 16, rig. 9).
K iitosolenia marginata var. lucida Williamson, 1848, p. 17, pi. 2,
fig. 17.
There are nine examples which are nearly circular in outline.,
and subcarinate. — Locality : No. 44.
PL 16, fig. 9. I believe this to be an elongate form of L. lucida,
in which the characteristic markings are only feebly represented.
The shell is very little compressed. Two or three specimens only
oocur. — Locality : Uncertain.
One or two tests are present which are intermediate between
the type and the elongate form referred to above. Several are
apiculate.— Locality : Nos. 1, 6, 14, 21, 22, 24, 38, 42, 43.
Lagena multicosta Karrer sp.
Fissurina multicosta Karrer, 1877, p. 379, pi. 16 6, fig. 20.
Fissurina bouei Karrer, p. 378, pi. 16 6, fig. 19.
The examples are small, and some are without the irregularity
of the costae characteristic of the type. — Locality : Nos. 24, 29, 34,
35, 39, 42-44, and one or two of the earlier stations.
Lagena fasciata Egger sp. (PI. 16, figs. 10-13).
Oolina fasciata Egger, 1857, p. 270, pi. 5, figs. 12-15.
PI. 16, fig. 10. Beautiful specimens occur which have the mouth
protruding, and the orifice composed of a line of pores. The
bands are flush or nearly so. Large and small tests are on the
slide. — Locality: Nos. 1, 3-5, 7, 10, 22, 44, and several other
stations which are uncertain.
PI. 16, fig. 11. An apiculate form wrhich is extremely rare.
The edge of the test is flattened, and has a very fine groove
running down its centre. The orifice appears to be composed of a
line of pores. — Locality : Uncertain.
PI. 16, fig. 12. Slightly apiculate, the orifice large, and the
entosolenian tube divided at the end. The edges of the bands,
which are not interrupted at the base, appear to be somewhat
raised. When the test is opaque it is difficult to make out the
bands. — Locality : Nos. 24, 34, 36, 43, 44 : frequent at No. 44.
PI. 16, fig. 13. The test is apiculate and the opaque bands
which appear to be flush with the surface are continuous — that is,.
184 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
not interrupted at the base as is usual in the type-form. About
thirty specimens on the slide. — Locality ; Nos. 42-44.
Lagena fasciata Egger sp. var. spinosa Sidebottom.
Lagena fasciata Egger sp. var. spinosa Sidebottom, 1912, Journ.
Q. M. C, p. 402, pi. 17, figs. 16, 17.
"*"P1. 17, fig. 16. One or two small specimens. — Locality:
Uncertain.
+ P1. 17, fig 17. A fair number are present, but they are
mixed with L. staphyllearia, so I cannot give the localities. See
remarks * p. 402.
Lagena fasciata Egger sp. var. carinata Sidebottom (PI. 16,
figs. 14-16).
Lagena fasciata Egger sp. var. carinata Sidebottom, 1906, Mem.
Pro. Lit. Phil. Soc, Manchester, No. 5, p. 7, pi. 1, fig. 17.
Lagena fasciata Egger sp. var. carinata Sidebottom, 1912, Journ.
Q. M. 6\, p. 403, pi. 17, fig. 18.
Pi. 16, fig. 14. The test is compressed, and the keel becomes
more pronounced as it approaches the base of the shell. The
internal tube is attached to the back of the test. A few of the
examples are very fine, like the one chosen for illustration. The
curved bands seem to be nothing more than an innumerable
number of pores showing distinctly. In some of the smaller
examples these bands can hardly be distinguished. It is open to
question if these forms and the following (PI. 16, fig. 15) would not
be better placed under L. marginata. — Locality : Nos. 1-3, 5-7,
10, 11, 13 22.
PI. 16, fig. 15. Test compressed, carinate. The entosolenian
tube is long and curled at its end. The bands are faintly marked
as in the preceding form. — Locality : Nos. 2-5 ; common at No. 2.
PI. 16, fig. 16. A solitary example. The edges of the curved
bands are very slightly raised, and the shell becomes more com-
pressed as the orifice is approached. The keel is represented by a
fine ridge only. The specimen is not in a very good condition,
opaque patches interfering with the definition of the bands,
especially at their bases. — Locality : No. 42.
+ PI. 17, fig. 18. Two or three examples found. The carina is
not pointed at the base as in the figure referred to.— Locality :
Uncertain.
HENRY S1DEB0TT0M ON LAGENAE OF THE SOUTH-WEST PACIFIC. 185
Lagena staphyllearia Schwager sp.
Fissurirta staphyllearia Schwager, 1866, p. 209, pi. 5, fig. 24.
The non-carinate form is rare. The number of spines varies.
The tube is attached to one side, thus causing the orifice to be
eccentric. In a few instances of the carinate variety, where only-
two spines are present, it is impossible to separate them from the
Fissurina bicaudata Seguenza, which is generally placed with L.
man/biota.— Locality ■ Nos. 1-7, 9-12, 15-25, 29, 33, 34, 36, 37,
39-43.
The variety with either the ketl or the lower part of the test
serrated or partially fimbriated is not so frequent, but occurs at
many localities. The orifice is central and the sides of the test
are only slightly carinate. — Locality : Nos. 5-8, 10, 11, 14, 15, 18,
19, 21, 22, 24, 33, 34, 40, 43.
+ P1. 17. fig. 19. Very rave.— Locality : Nos. 2, 3, 15, 22.
+ P1. 17, fig. 21. This peculiar variety is rather rare. The
tests are semi-opaque. There is a short entosolenian tube. —
Locality : Nos. 5-11, 13, 21, 23, 25, 36, 39, 40.
+ P1. 17, figs 22, 23. See remarks * p. 403. — Locality: Nos.
4-6, 8, 10, 22, 23, 33, 39.
Lagena staphyllearia Schwager sp. var. quadricarinata
Sidebottom.
Lagena staphyllearia Schwager sp. var. quadricarinata Sidebottom,
1912, Journ. Q. M. C, p. 404, pi. 21, fig. 16.
Locality .- Nos. 2, 5-7, 9, 10, 12, 13, 21, 38, 41.
Lagena unguiculata Brady.
Lagena unguiculata Brady, 1881. Quart. Journ. Micr. Sci., vol. 21,
(N.S.), p. 61.
-Lagena unguiculata Brady, 1884, p. 474, pi. 59, fig. 12.
See remarks + p. 404. — Locality : Nos. 5-10.
Lagena quadrata Williamson sp.
-Entosolenia marginata var. quadrata Williamson, 1858, p. 11, pi. 1,
fig. 27.
Both the carinate and non-carinate form are present. — Locality :
Nos. 15, 22, 24, 25, 34, 37, 40, 42-44.
Journ. Q. M. C, Series II.— No. 73. 13
186 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
There are several' examples which have a short neck and the
orifice carrying a short spine at either side. Three or four
specimens are similar to the one figured by Mr. Millett in his
Malay Report, 1901, p. 496, pi. 8, fig. 18.
Lagena marginata Walker and Boys sp. (PI. 16, figs. 17-20,
fig. 18, trifacial form).
" Serpula {Lagena) marginata" Walker and Boys, 1784, p. 2,.
pi. 1, fig. 7.
This species is exceedingly well represented in these gatherings,
and in one form or another is found at nearly all the stations.
The shape of the body of the test varies from flattened to globular,
and in outline from circular to elongate-pyriform, the carination
from a fine ridge to a very broad wing. The situation and form
of the orifice are variable. Apiculate examples are present and
some have the keel acuminate at the base.
PI. 16, fig. 17. This agrees fairly well in outline with Fissurina
paradoxa Seguenza, 1862, pi. 2, fig. 7. The Fissurina bicaudata
Seguenza, 1862, pi. 2, fig. 16, is also represented, and it is difficult
in some cases to separate this from L. staphyllearia.
PI. 16, fig. 18. A trifacial form. If anything, the three faces
of the body are somewhat concave ; one would rather expect them
to be convex, judging from trifacial examples that occur in other
species. The specimens vary very little. — Locality ; Nos. 2-4,
8-10, 14, 15, 22, 29, 34, 36, 39, 40.
PI. 16, fig. 19. The edge of the test is flattened, the orifice
fissurine. In some positions it has the appearance of being
slightly bicarinate, but I do not think it is so. — Locality : Nos.
42, 43.
PI. 16, fig. 20. This minute variety has a comparatively large
orifice, which is much compressed and opens out on one side of
the median line ; the tube is attached to the back of the test,
which is very slightly carinate. The test is moderately com-
pressed and curiously tucked in at its base. The specimens are
mixed with others very similar to them, but which have the
orifice central and the tube short and straight. There are other
forms on the same square, so I cannot give the exact localities.
The two forms mentioned are rare. Both were found at a station
later in the series than ISTo. 22.
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 187
Lagena compresso-marginata Fornasini (PI. 16, fig. 21).
Lagena compresso-marginata Fornasini, 1889, Minute Forme di
Riz. Retic. nella Mama Plioc. del Ponticello di Savena,
Bologna, fig. 16.
PI. 16, fig. 21. This is rather a stoutly-built form. The aperture
is fissurine and the test apiculate. — Locality : Nos. 22, 24.
Rather rare.
There are a few very small examples that appear to be almost
identical with Fornasini's figure. — Locality : Uncertain.
+ PI. 17, fig. 30. Only two or three found. — Locality: Nos.
42, 44, and two or three examples at one or two other stations.
+ PI. 17, fig. 31. Very rave. — Locality ; Nos. 2, 4.
*** PI. 18, fig. 1. Very rare. See remarks + p. 406. — Locality ;
Nos. 2, 5, 7, 19, 24.
Lagena marginata Walker and Boys var.
Lagena marginata Walker and Boys var. Sidebottom, 1912,
Journ. Q. M. C, p. 407, pi. 18, figs. 4, 5.
Locality: Nos. 4-6, 10-13, 16, 17, 19-23, 25, 36, 40.
Lagena marginata Walker and Boys var. catenulosa Chapman
(PL 16, fig. 22).
Lagena marginata var. catenulosa Chapman, 1895, p. 28, pi. 1, fig. 5.
Lagena marginata Walker and Boys var. catenulosa (Chapman)
Sidebottom, 1912, Journ. Q. M. C, p. 407, pi. 18, fig. 6.
PI. 16, fig. 22. Four examples occur. The one chosen for
illustration hardly shows a trace of the chain-pattern, and the
test is free from exogenous shell-growth. The others show the
chain-pattern. One of the specimens has the body of the test
covered with exogenous beads. The few tubuli shown in the
drawing are caused, I believe, by the borings of some animal. — ■
Locality : Nos. 1, 5, 10.
Lagena marginata Walker and Boys var. raricostata
Sidebottom.
Lagena marginata Walker and Boys var. raricostata Sidebottom,
1912, Journ. Q. M. C, p. 408, pi. 18, figs. 8, 9.
*'r PI. 18, fig. 8. Over twenty specimens are on the slide. —
Locality : Nos. 1-3.
18S HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
Lagena marginata Walker and Boys var. striolata Sidebottom.
Lagena marginata Walker and Boys var. striolata Sidebottom,
1912, Journ. Q. M. C, p. 408, pi. 18, figs. 10, 11.
+ P1. 18, fig. 10.— Locality: Nos. 1, 3, 4, 15, 18-20, 22-25, 34,
35, 38, 42-44 ; frequent at Nos. 42, 43.
+ PI. 18, fig. 11.— Locality : Nos. 23, 24, 42.
Lagena marginata Walker and Boys var. elegans Sidebottom.
Lagena marginata Walker and Boys var. elegans Sidebottom,
1912, Journ. Q. M. C, p. 409, pi. 18, fig. 12.
Locality : Nos. 14, 19, 20 ; frequent at No. 14.
Lagena marginata Walker and Boys var. retrocostata
Sidebottom.
Lagena marginata Walker and Boys var. retrocostata Sidebottom,
1912, Journ. Q. M. C, p. 409, pi. 18, fig. 13.
Locality : One specimen at No. 2, and one other, station un-
certain.
Lagena marginata Walker and Boys var. semimarginata
Reuss.
Lagena No. 64, von. Schlicht, 1870, p. 11, pi. 4, figs. 4-6; and
Xo. 65, p. 11, pi. 4, figs. 10-12.
Lagena marginata var. semimarginata Reuss, 1870, p. 468.
An altogether unsatisfactory variation. It occurs in several
forms at a few stations ; that figured in the Challenger Report,
pi. 59, fig. 19, occurs at No. 44.
Lagena marginata Walker and Boys var. seminiformis
Sch wager.
Miliola stiligera Ehrenberg (?) 1854, pi. 31, fig. 6.
Lagena seminiformis Schwager, 1866, p. 208, pi. 5, fig. 21.
Four large examples occur, similar to those figured in the
Challenger Report, pi. 59, figs. 28-30. — Locality; Nos. 5, 16, 17.
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 189
"*" PI. 18, fig. 16. Extremely rare, only one or two being found.
— Locality ; Uncertain.
"i" PI. 18, fig. 17. — Locality-. Nos. 1-3, 15. Three examples at
two or perhaps three of the four stations indicated ; also six at a
few other uncertain localities.
+ PI. 18, fig. 18. — Locality: Nos. 1, 3, 13, and several others.
Very rare.
**■ PI. 18, fig. 19. Several have the central spine at the base of
the same length as the other two. — Locality : Nos. 2, 3, 6-8, 10,
11, 24, 34-36.
Lagena marginato-psrforata Seguenza (PI. 16, figs. 23-25).
Lagena marglaato-perforata Seguenza, 1880, p. 332, pi. 17, fig. 34.
Very numerous. The variety with no keel is rare. The shape
of the test varies a good deal as regards compression and length.
In a few cases, fine lines, running the length of the test, make
their appearance. At the edge of the test, the markings are
sometimes arranged in a line. — Locality : Nos. 1, 2, 4, 5, 7-15, 19,
20, 22-25, 29, 38-40, 42-44.
PI. 16, fig. 23. This is nearly circular in section near the base,
and becomes compressed as the orifice is approached. Tube
straight. Ptare. — Locality : No. 14.
PI. 16, fig. 24. In this example fine pores are seen, but with
few exceptions the centre of each face of the test is free from
them. One specimen is in the trifacial condition. — Locality ;
Nos. 23-25, 29, 33, 36, 38, 39.
PI. 16, fig. 25. Test well compressed, subcarinate. Except for
the two lines of pores that run round the test close to its edge,
the faces are almost free from them. The shell is partially
clouded. Fairly frequent. — Locality : Uncertain.
Lagena Wrightiana, Brady.
Lagena Wrightiana Brady, Quart. Journ. Micr. ScL, vol. 21,1881,
p. 62.
Lagena Wrightiana Brady, 1884, p. 482, pi. 61, figs. 6, 7.
The central part of the faces of the test is not always smooth.
Very rare. — Locality : Nos. 37, 42, 43.
190 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
Lagena lagenoides Williamson sp. (PI. 16, figs. 26-29, and
pi. 17, fig. 1).
Entosolenia marginata Walker and Boys var. lagenoides
Williamson, 1858, p. 11, pi. 1, figs. 25, 26.
This and its numerous variations are well represented. PI. 16,
figs. 26, 27. I was tempted to place these under L. marginata,
but the appearance of the wing caused me to hesitate and to
submit a specimen to Mr. Earland for examination. He reported
that the wing was tubulated, being " infiltrated with amorphous
carbonate of lime subsequent to the death of the animal." Mr.
Millett considers that if tubuli are present " their affinity would
be with L. lagenoides rather than with L. marginata." Besides
the two forms figured, both large and small circular examples
occur in the same condition, only with the tubuli showing more
plainly.
PI. 16, fig. 28 represents one of the small examples. There are
also specimens which are apparently of exactly the same form, in
which the tubuli, if present, must be extremely minute. It would
appear therefore necessary to submit all such forms to critical
examination. — Locality : Nos. 5-7, 11, 14, 15, 18-22.
PI. 16, fig. 29. In this instance the keel is twisted at the base.
Four specimens found. — Locality : Uncertain, but after station
No. 22.
PI. 17, fig. 1. The test is well compressed and the orifice also.
Entosolenian tube short and curled. —Locality : Ncs. 42-44 ;
frequent at Nos. 43, 44.
+ P1. 18, fig. 22. The form occurring is very similar to the
figure referred to. It is rather smaller and the keel is narrower
and thicker ; the neck and phialine orifice are the same. — Locality ;
Nos. 1-3, 42-44.
Six large specimens similar to the Challenger Report figure,
pi. 60, fig. 14, are also present. Very rare. — Locality : Nos. 2,
22, 24.
Another set is similar to +pl. 19, fig. 4, but the tests are not
striated. Frequent. — Locality : Nos. 2-8, 11.
+ PI. 18, fig. 23. See remarks, +p. 412.— Locality : Nos. 2, 36,
38, 39.
+ P1. 18, fig. 29. Typical examples are very rare and not so
HENRY SIDEBOTTOM OX LAGENAE OF THE SOUTH-WEST PACIFIC. 191
large as the specimen referred to. — Locality : No. 3, and either
No. 35 or 39.
Besides the above, there are a few specimens which are much
smaller, especially in the width of the test. — Locality : Nos. 17,
19, and one or two other stations.
Lagena lagenoid.es Williamson sp. var. nov. duplicata
(PI. 17, fig. 2).
The test is bicarinate ; aperture oval and the keels tubulated.
Six specimens found. — Locality : Nos. 24, 37.
Lagena lagenoides Williamson sp. var. tenuistriata Brady.
Lagena tubulifera var. tenuistriata Brady, 1881, Quart. Joiirn.
Micr. Sci. vol, 21 (N.S.), p. 61.
Lagena lagenoides Williamson var. tenuistrata Brady, 1884, p. 479,
pi. 60, figs. 11, 15, 16.
*P1. 19, fig. 4. Very frequent. These correspond to the
Challenger Report, pi. 60, fig. 11. The trifacial form also occurs.
—Locality ; Nos. 1-11, 13, 14, 17, 21-24, 29, 31, 33-35, 37, 39-41.
There is another set of specimens which are not quite so large
and have the costae on the body of the test, farther apart. —
Locality : Nos. 14, 15, 17, 18.
There are a few large specimens very similar to the Challenger
Report, pi. 60, fig. 15. In the stouter examples the fine costae
■coalesce to such an extent that the surface has a pitted appear-
ance.— Locality: Nos. 2, 8, 11, and one or two other stations.
Lagena formosa Schwager (PI. 17, figs. 3-7).
Lagena formosa (pars) Schwager, 1866, p. 206, pi. 4, fig. 19.
Lagena formosa (Schwager) Brady, 1884, p. 480, pi. 60, figs. 10,
18-20.
This is present in many forms ; some show the raised border
punctate, others do not. See remarks **" p. 414.
PI. 17, fig. 3. In this, which is obviously of the same kind as
fig. 18, pl. 60, in the Challenger Report, the raised border is
absent. Others agree with this figure, also with the Challenger
Report, fig. 20.
Several very fine specimens are intermediate between fig. 18
and L. formosa var. favosa Brady, on the same plate, fig. 21.
192 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACTFIC
They are heavily punctate at the base of the neck, and costae just
start to run clown the keels. Many small examples occur, which
come under this unsatisfactory species, but as they are mixed on
the various squares I can only give the stations for the whole
series.— Locality : Nos. 1-8, 10, 11, 13, 14, 17, 21, 23-25, 29,
37, 39-41, 43.
PI. 17, fig. 4. The keel splits near the top, and the space thus
formed is filled with shell-growth. The specimens are not in a
satisfactory condition for examination, so I cannot say if the
tubuli in the keel occupy the whole of the space. The punctate
border does not seem to be raised, and it shows clearer in substance
than the rest of the test. I believe this is the same as Challenger
Report, pi. 60, fig. 10.— Locality : No. 44.
PI. 17, fig. 5. T am inclined to believe that the keel has broken
away in these specimens, of which there are seven. They are all
in the same condition ; the drawing shows how the keel has
begun to split. — Locality .• Nos. 43, 44.
+ PI. 18, fig. 24. I am now inclined to believe that in this
case also the keel has become fractured.
PI. 17, fig. 6. This has a likeness to the preceding pi. 17, fig. 5.
The keel, which commences at the neck, soon splits and joins the
two borders ; the space between them is filled with shell-growth.
The test has a very compact look and the tubuli show clearly.
Rare. — Locality : Nos. 42, 43.
PI. 17, fig. 7. A solitary specimen in good condition. The keel,
commencing at the orifice, dies away about half-way down the
test. A few well-marked pores are scattered on each face of the
test. At the base are several short costae. — Locality ; No. 37.
+ P1. 19, fig. 9. See remarks, + p. 414. Frequent. — Locality :
Nos. 1, 2, 10, 11, 14, 17-19, 22. Over twenty examples occur after
station No. 22, but the exact stations are uncertain.
Lagena formosa Sch wager, var. (PI. 17, fig. 8).
The drawing of this variety must be taken more or less as
diagrammatic. The test, which has three keels (the central one
commencing at the aperture) is in an opaque condition. The
spaces between the keels are filled with shell-growth. The tubuli
hardly show, unless the shell be moistened. The body of the test
has fine costae running lengthwise, and is finely pitted. There*
HENRY SIDEBOTTOM ON LAGEXAE OF THE SOUTH-WEST PACIFIC. 193
are only two specimens and they are exactly alike. — Locality .-
No. 40.
Lagena formosa Schwager var. comata Brady.
Lagena formosa var. comata Brady, 1884, p. 480, pi. 60, tig. 22.
A few large specimens occur very similar to the Challenger
examples, pi. 60, tig. 22. — Locality : Nos. 5, 6, 33, 34.
+ P1. 19, fig. 11. A single example. — Locality: Uncertain.
+ P1. 19, fig. 12. Very rare.— Locality : Nos. 6, 10, 22, and
one or two stations which are uncertain.
Lagena squamoso-alata Brady (PI. 18, fig. 20).
Lagena squamoso-alata Brady, 1881, Quart. Journ. Jlicr. Sci.
vol. 21 (N.S.), p. 61.
Lagena squamoso-alata Brady, 1884, p. 481, pi. 60, fig. 23.
A single example occurs, which is typical, except that the
produced neck is absent, having most probably been broken off. —
Locality : No. 23.
PI. 18, fig. 20. Besides the above typical specimen, there are
twenty-two tests which are smaller and not so robust. They
answer to Brady's description of the species. The pittings on the
body of the test have a tendency at times to arrange themselves
in lines. The raised border appears to be punctate. It is
difficult to make out the markings on the wings, owing to debris,
but they can be detected in some of the specimens. I believe the
wings to be cellulated. Brady, in the Challenger Report, only
mentions that they have radiate markings ; but on examining the
edges of my typical specimen it is apparent that the wings are
cellulated. I take this form to be simply a variety of L. formosa.
One example is in the trifacial condition. — Locality ; Nos. 24, 25,
34, 36.
Lagena quadrangularis Brady.
Lagena quadrangularis Brady, 1884, p. 483, pi. 114, fig. 11.
Lagena quadrangularis (Brady) Millett, 1901, p. 625, pi. 14,
% IT.
A single typical specimen, but the neck appears to be fractured.
— Locality ; Either No. 14 or No. 22.
194 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
Lagena Orbignyana Seguenza sp. (PI. 17, figs. 9-11).
Entosolenia mdrginata (pars) Williamson, 1858, p. 10, pi. 1, figs.
19, 20.
Fissurina Orbignyana Seguenza, 1862, p. 66, pi. 2, figs. 25, 26.
This occurs in many forms. Some of the specimens are similar
to the Challenger Report, pi. 59, figs. 25, 26. Numerous small
varieties also are present. In some the side keels are little more
than slightly raised ridges.
PI. 17, fig. 9. This is a very neat and compact variety.
The test is moderately compressed. — Locality : Nos. 42-44 ;
frequent at Nos. 42, 44.
PI. 17, fig. 10. I take this to.be a variety of L. Orbignyana, in
which the central keel has split soon after leaving the orifice.
The body of the test is much compressed, and is roughened. The
entosolenian tube is long and attached. The split keel is entirely
blocked wTith debris, or shell-growth. Two examples found. —
Locality : No. 38.
PI. 17, fig. 11. A neat form. The central keel is emarginate
at the base, at the middle of which one or two small spines
project. The two subsidiary keels are not generally continuous.
There are over one hundred specimens. — Locality : Nos. 1, 2, 4-13,
21, 23, 26, 29, 33, 34, 38, 39.
Lagena Orbignyana Seguenza sp. var. lacunata Burrows and
Holland (PI. 17, fig. 12).
Lagena lacunata (Burrows and Holland) Jones, 1895, p. 205, pi. 7,
fitf 12
One set agrees exactly with fig. 1, pi. 60 of the Challenger
Report, which Messrs. Burrows and Holland point out in the
above reference, is misnamed as L. castrensis Sch wager. — Locality :
Nos. 42-44 ; frequent at No. 44.
A few small examples are occasionally met with in which the
pittings are numerous and minute, and the keels very feebly
developed. — Locality : Uncertain.
PI. 17, fig. 12. I am treating this as a form of X. Orbignyana
var. lacunata, but it appears to have one of the characteristics of
L. annectens (Burrows and Holland) Jones, 1895, for the band
round the body of the test appears to be very slightly concave.
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 195
The edges of the band are just raised above the surface, and the
space between is roughened. It will be noticed, by reference to
the Challenger figure, pi. 60, fig. 1, that there is a ridge, or minor
keel, between the side keel and the central one, and I take my
specimens to be in the same condition, only the inner ridge is
quite close to the central keel. The body of the test is finely
pitted all over. The aperture is large, compressed and lipped.
In two cases the keel is serrated all round, but it is doubtful if
this is natural. The tube is attached. Frequent. — Locality :
Nos. 42, 43.
Lagena Orbignyana Seguenza sp. var. Walleriana Wright.
Lagena Orbignyana sp. var. Walleriana Wright, 1886, Proc. JR. Irish
Acad., ser. 2, vol. iv., p. 611, and 1891, p. 481, p. 20, fig. 8.
In all the specimens the typical boss is replaced by a ring,
which is very slightly raised. — Locality: Nos. 2, 22, and one or
more of the three stations, Nos. 42-44.
Lagena Orbignyana Seguenza sp. var. unicostata Sidebottom.
Lagena Orbignyana Seguenza sp. var. unicostata Sidebottom,
1912, Journ. Q. M. C, p. 417, pi. 19, fig. 22.
The single costa in this case runs the whole length of the body
of the test. Very rare. — Locality ; Nos. 18, 22.
Lagena Orbignyana Seguenza sp. var. pulchella Brady
(PI. 17, fig. 13).
Lagena pulchella Brady, 1866, Rept. Brit. Assoc. (Nottingham),
p. 70.
Lagena pulchella Brady, Annals and Mag. Nat. Hist., 1870, p. 294,
pi. 12, fig. 1.
The largest specimens are very similar to L. Orbignyana var.
variabilis Wright, 1891, pi. 20, fig. 9, but the costae are irregular
and cover the whole of the body of the test ; sometimes there is
a fine ridge showing between the main keel and the side keels.
Very rare. — Locality : Uncertain.
A smaller set is frequent, with few and irregular costae. The
side keels amount to little more than slight ridges. — Locality :
No. 44.
196 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC*
A few very small examples are also present.
PI. 17, fig. 13. This solitary example has the eostae well raised,
and as they are irregular I have placed it under the above head-
ing. The side keels are only just apparent. — Locality : No. 44.
+ P1. 19, fig. 24. Very rare. See remarks + p. 418. — Locality .-
Nos. 1, 38.
Lagena Orbignyana Seguenza sp. var. clathrata Brady
(PI. 17, fig. 14).
Lagena clathrata Brady, 1884, p. 485, pi. 60, fig. 4.
The type-form occurs, but is always rare, except at No. 43,
where eleven were found. — Locality: Nos. 17, 18, 24, 29, 35, 37,
38, 43, 44.
A few very small specimens are present, but they are not
typical. Others are minute, with numerous fine eostae either
straight or curved, these latter resembling L. variabilis, as Mr.
Millett remarks in his Malay Report, 1901, p. 628.
PL 17, fig. 14. I think this may be brought under the above
heading. The test is compressed and has three keels ; these
stand out more than the three eostae which run down each face
of the test. — Locality : Nos. 8, 10-14 ; frequent at No. 8.
Lagena Orbignyana Seguenza sp. var. variabilis Wright.
Lagena Orbignyana sp. var. variabilis Wright, 1890, p. 482, pi.
20, fig. 9.
Except that the side keels are not so well developed, and the
striae are very numerous, the specimens are fairly typical. In
several instances the striae are inclined to cover the body of
the test, and in others they are either absent or scarcely per-
ceptible.— Locality .- 2, 5-7, 10-14, 16-18, 24, 29, 34, 35.
Lagena Orbignyana Seguenza sp. var. (PI. 17, fig. 15).
The test is only slightly compressed ; the main keel, which
starts at the orifice, splits as it approaches the body of the test.
Very fine bars cross the space thus formed. Between the cross-
bars is a well-marked circular depression. Besides the side keels
there are two semicircular eostae, one of these on each face of
the test. At the base is an irregular circular projection to which
the keels are attached. The wall of this projection is thin.
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 197
0
Onlv two specimens were found, each of them badly fractured.
Both have been utilised in preparing the illustration, which must
be considered as a drawing of a restored specimen. — Locality;
Uncertain.
Lagena bicarinata Terquem pp. (PI. 17, figs. 16, 17).
Fissurina bicarinata Terquem, 18827 p. 31, pl. 1 (9), fig. 24.
The type-form does not appear to be present.
PI. 17, fig. 16. The tests are in a very opaque condition. —
Locality: Nos. 23, 24, 33, 34, 40.
PI. 17, fig. 17. There are two or more spines at the base.
Eleven specimens are in good condition. — Locality : Nos. 2-3.
+ PI. 19, fig. 27. See remarks + p. 419.— Locality ; Nos. 2-4.
A few also occur, very similar to these, except that the body of
the test is more circular in outline. — Locality : Uncertain.
Lagena bicarinata Terquem sp. var. (PI. 17, fig. 18).
Test bicarinate. The faces of the test are slightly convex, and
the two keels slope towards their edges, the effect being that the
test appears to have a boss on either face. Orifice much com-
pressed and composed of a row of pores. A solitary specimen. —
Locality : No. 37.
Lagena bicarinata Terquem sp. var. (PI. 17, fig. 19).
Test bicarinate and apiculate, with a row of very short tubular
projections running round the edge of the test between the keels.
The test becomes more compressed as the orifice is approached.
Two examples only occur. The neck appears to be broken olT in
both cases. — Locality: No. 43.
Lagena bicarinata Terquem sp. var. (PI. 17, fig. 20).
Test bicarinate, the keels generally dying away as they
approach the orifice, which is composed of a series of fine pores.
I cannot say if the fine bands, which adorn each face of the test,
a,re raised or not. Bands of different nature and length are
found on other species besides L. fasciata, so I prefer to place this
form under L. bicarinata, instead of treating it as L. fasciata in
the bicarinate condition. — Locality : Nos. 1-10, 13, 15, 16.
198 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC
Lagena auriculata Brady (PI. 17, figs. 21, 22, and pi. 18,
fig. 1).
Lagena auriculata Brady, 1881, Quart. Journ. Jlicr. Sri., vol. 21
(N.S.), p. 61.
Lagena auriculata Brady, 1884, p. 487, pi. 60, figs. 29, 31, 33.
This is largely represented, especially in its variations ; inter-
mediate forms occur which it would be interesting to figure.
PI. 17, fig. 21. In this solitary specimen the wing has divided
at a point a little above the body of the shell. — Locality ; No. 2&
or No. 39.
PI. 17, fig. 22. A neat form which appears to be strongly
built. The shell is moderately compressed. The entosolenian
tube, when present, is very short and straight. The orifice is
crowned with a boss, and the loops at the base are feebly
represented. Nine specimens occur. — Locality ; Nos. 2, 10.
PI. 18, fig. 1. A stoutly-built form. The test is subcarinate,.
and the orifice situated in a depression. The two loops at the
base are feebly developed. Very rare. — Locality ; Uncertain, but-
after station No. 23.
"** PI. 20, fig. 4. A few examples resemble this variation, the
keel being continuous round the edge of the test. — Locality : Nos.
23, 24, 26, 36, 38, 40, 42, 43.
"*" PI. 20, fig. 5. There are twelve examples, closely resembling
this figure, but having no small wings at the top of the test. —
Locality : Nos. 24, 29, 34, 36, 39-41.
**" PI. 20, figs. 7. 8. A large number are similar to these forms
and to Challenger Report, pi. 60, fig. 29. — Locality : Nos. 2-4,.
6-12, 17-24, 26 29, 33 35, 38 43.
+ P1. 20, figs. 9, 10. Some forms present lie more or less
between the two figures given at this reference. — Locality; Nos.
2-6, 6-11, 17, 18, 21, 22.
+ P1. 20, figs. 11, 12. Only two or three specimens are near
+ fig. 11 ; all the rest, and there are over eighty, are like + fig. 12.
—Locality .- Nos. 1-11, 22, 23, 33, 34, 37, 39. Most of them were
found at Nos. 1-11.
"*"P1. 20, fig. 13. Nine examples occur, and one is in the
trifacial condition. — Locality ; Nos. 1, 38, 42 44 : the trifacial
specimen at No. 43.
*P1. 20, fig. 14. Eight specimens found. — Locality; Nos. 1-4.
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 199
Lagena auriculata Brady var. nov. caudata (PI. 18, figs. 2, 3).
Test compressed, the lower part of the body faintly striated.
A single long spine, probably always bent more or less to one
side, projects at the base. Orifice situated at the end of a long
neck. In fig. 2 the basal spine is partly broken off.
The faint striation seems to indicate an affinity with L. auricu-
lata var. costata Brady, but in order to avoid giving subvarietal
names, I have treated it as a variation of L. auriculata. —
Locality : No. 2.
Lagena auriculata Brady var. nov. circunicincta (PI. 18, fig. 4).
Test compressed, subcarinate, except at the lower edge and
base, where the keel is well developed. A few costae run across
each face of the test. Orifice oval. Entosolenian tube long and
curved. Four specimens occur. There are six tests on the
square, but two do not belong to the same variety. — Locality .-
No. 43, and one of the following stations : Nos. 38, 42, 44, but
which one is doubtful.
Lagena auriculata Brady var. nov. clypeata (PI. 18, fig. 5).
Test compressed, carinate. Orifice oval. Two raised oval
rings (sometimes slightly irregular) on each face of the shell.
The loops at the base small. Entosolenian tube long and curved.
It is easy to miss noticing the loops. The tests vary a little
from one another in outline. The keel is not quite so wide as
indicated in the drawing.
About twenty specimens are arranged on the same square as a
number of L. Orbignyana sp. var. Waller iana Wright, for which
they may have been temporarily mistaken. — Locality : The
majority must have been found either at Nos. 42 or 43, or both.
Lagena auriculata Brady var. Sidebottom (PI. 18, fig. 6).
Lagena auriculata Brady var. Sidebottom, 1912, Journ. Q. M. C.r
p. 421, pi. 20, figs. 15-18.
Pi. 18, fig. 6 and * pi. 20, fig. 15. I have figured one of
average size. There are often a few spines at the base. —
Locality ; Nos. 4, 23, 24, 38-44.
A few elongate examples occur. — Locality ; Nos. 2. 3-
.200 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC
Several approach + pi. 20, fig. 18. — Locality : Uncertain.
+ PI. 20, fiff. 17. A number are near this form, and mixed
^vvith them are several identical with Mr. Millett's Malay Report,
pi. 14, fig. 15.— Locality : Nos. 1-4.
A few elongate specimens occur, the body being striated, or
^wrinkled, as indicated in the figure. — Locality : Nos. 8, 9, 11.
Lagena auriculata Brady var. arcuata Sidebottom.
Lagena auriculata Brady var. arcuata Sidebottom, 1912, Journ.
Q. M. C, p. 421, pi. 20, figs. 19, 20.
+ PI. 20, fig. 19. The specimens differ from the figure, as the
arches radiate from the base. — Locality : Nos. 4-7, 9, 10.
Lagena auriculata Brady var. costata Brady.
Lagena auriculata Brady var. costata (Brady) Sidebottom, 1912,
Journ. Q. M. C, p. 422, pi. 20, figs. 21, 22.
* Pi. 20, fig. 22. See remarks, + p. 422.— Locality : Nos. 23,
24, 29, 33, 39~ 42.
Lagena auriculata Brady var. duplicata Sidebottom
(PI. 18, figs. 7, 8).
Lagena auriculata Brady var. duplicata Sidebottom, 1912, Journ.
Q. M. a, p. 422, pi. 20, fig. 23.
Pi. 18, fig. 7. The loops in this case extend from the base
almost to the neck. At the first glance, I took the specimens to
be L. Orbignyana, as in some of the specimens debris or shell-
growth partially covered the loops, the inner sides of which are
quite close to the keel ; a closer examination of other examples,
which are free from debris, show the loops to be complete.
The tests, of which there are tan, are large. — Locality : No. 42.
Note. — The above might, with equal propriety, be treated as
a carinate form of L. alveolata var. separans Sidebottom, 1912,
■+pl. 21, fig. 4.
PL 18, fig. 8. This differs from + PI. 20, fig. 23, chiefly in the
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 201
absence of the carina. Very rare. — Locality : Nos. 29. 34, 39.
Two or three were found at other stations besides those indicated.
Note. — Several examples occur almost identical with the above ;
the only difference being that the loops merge together as in
L. alveolata, and so must be treated as such.
* PI. 20, fig. 23. One specimen. Locality: Uncertain.
Lagena fimbriata Brady (PL 18, tig. 9).
Lag ena fimbr lata Brady, Quart. Journ. Micr. Sci., vol. 21 (N.S.),
1881, p. 61.
Lagena fimbriata Brady. 1884, p. 486, pi. 60, figs. 26-28.
Two specimens occur similar to the Challenger Report, pi. 60,
fig. 28. — Locality : Uncertain.
Pi. 18, fig. 9. This is a neat, small, compactly built variety,
and the fimbriated portion does not appear liable to get fractured.
The tube is curled upon itself. The test is moderately com-
pressed, and the opening at the base is very narrow. This variety
must not be confused wTith pi. 20, fig. 28. — Locality : Nos. 31, 43,
44 ; frequent at No. 44.
+ PI. 20, fig. 24. Two examples only occur. — Locality :
No. 31.
+ P1. 20, fig. 25. Eight specimens. — Locality : One or more of
the following stations : Nos. 5, 6, 22.
+ PI. 20, fig. 26. Four very fine examples occur. — Locality :
Nos. 4, 6, 8, 10.
Three specimens, with the base more pointed and the opening
more contracted, are also on the slide. — Locality : Nos. 7, 10, 12.
Lagena fimbriata Brady var. nov. duplicata (PI. 18, fig. 10).
Test compressed, ovate. There are two narrow loops, side by
side, across the width of the test at its base. Tube curled on
itself. I think the walls of the loops are tubulated, but cannot
be quite certain about it. A solitary specimen. — Locality:
Uncertain.
There is another test which has the orifice wider, and the tube
short and straight. The loops are in the same position, but so
feebly represented that it is doubtful whether it belongs to the
above variety.
Journ. Q. M. C, Series II. — No. 73. 14
202 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
Lagena fimbriata Brady var. occlusa Sidebottom.
Lagena fimbriata Brady var. occlusa Sidebottom, 1912, Journ..
Q. M. C, p. 423, PI. 20, figs. 27, 28.
+ PI. 20, fig. 27. Common. Most of the specimens have the
opening at the base more open than in the illustration. See
remarks, + p. 423.— Locality: Nos. 1-4, 6-13, 15, 17, 19, 22, 24,
25, 29, 31, 33-35, 37-42.
Lagena alveolata Brady (PI. 18, figs. 11, 12).
Lagena alveolata Brady, 1884, p. 487, pi. 60, figs. 30, 32.
PL 18, fig. 11. The tests are large and strongly built. All are
in the apiculate condition. The dotted line indicates the
boundary of the chamber, thus showing the thickness of the
wall. Orifice oval. Twelve examples occur. — Locality : Nos. 1, 5.
PL 18, fig. 12. There are a large number present. The tests
are fairly well compressed. The chief peculiarity is that, though
the entosolenian tube is straight, the orifice opens out well below
the median line. The part above the j orifice is sharpened. The
loops at the base are small, and their outer edges do not project
nearly so far as does the central carina. — Locality : Nos. 1-15,
17-20.
"** PL 21, fig. 1. Unfortunately the specimens are mixed with
another species, so that the stations at which they were found
are uncertain. There are a fair number on the slide.
**" PL 21, fig. 2. Good examples are present. — Locality : Nos. 1,
3-5, 7, 10, 16, 17.
Lagena alveolata Brady var. carinata Sidebottom.
Lagena alveolata Brady var. carinata Sidebottom, 1912, Journ.
Q. M. C, p. 424, pi. 21, fig. 3.
This form is very rare in this collection. — Locality : Nos. 24,.
39, 40.
Lagena alveolata Brady var. substriata Brady.
Lagena alveolata var. substriata Brady, 1844, p. 488, pi. 6, fig. 34.
A single specimen. It is not quite typical, the neck of the
test being more produced than in the Challenger figure. —
Locality : No. 39.
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 203
Lagena alveolata Brady var. separans Sidebottom.
Lagena alveolata Brady var. separans Sidebottom, 1912, Journ.
Q. M. C, p. 425, pi. 21, fig. 5.
Locality: Nos. 1-3, 5, 6, 17-20, 23-25, 34, 38.
Lagena clypeato-marginata Rymer-Jones var.
Lagena clypeato-mavginata Rymer- Jones var. Sidebottom, 1912,
Journ. Q. 21. C, p. 425, pi. 21, fig. 6.
Several examples occur. — Locality : Uncertain.
Lagena magnifica Sidebottom.
Lagena magnifica Sidebottom, 1912, Journ. Q. M. 6'., p. 425,
pi. 21, fig. 8.
A few of the specimens are in the transparent condition. —
Locality : ]S"os. 1-5, 7.
Lagena Elcockiana Millett.
Lagena Elcockiana Millett, 1901, p. 621, pi. 14, figs. 5, 6.
Lagena Elcockiana (Millett) Sidebottom, 1912, Journ. Q. M. C,
p. 426, pi. 21, fig. 9.
A single specimen. — Locality : Uncertain.
Lagena galeaformis Sidebottom.
Lagena galeaformis Sidebottom, 1912, Journ. Q. M. C, p. 426,
pi. 21, figs. 11, 12.
+ P1. 21, fig. 12. Only the trifacial form appears to be repre-
sented in these gatherings. — Locality : Nos. 1-3.
There are a few tests which may, or may not, be the bifacial
form of this species. I have included them under **"pl. 20, fig. 17,
on page 421. They are not so stout as this figure represents,
and the side keels are entire as far as the tubular process.
Lagena protea Chaster.
Lagena protect Chaster, 1892, p. 62, pi. 1, fig. 14.
See remarks, + p. 427 .—Locality : Nos. 2, 10, 17, 19, 22, 23, 25,
38, 39, 43, 44.
204 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC
Lagena invaginata sp. nov. (PL 18, fig. 13).
Test slightly carinate ; oral end protruding and arched ;
orifice a narrow slit, perhaps barred. The front highly convex ;
the back flat, with a large concave recess at the base. The
entosolenian tube long and bent to one side. Twenty-one
examples occur. — Locality : Nos. 38, 41, 42 ; chiefly at No. 42.
Lagena reniformis sp. nov. (PI. 18, fig. 14).
The test reminds one of a kidney bean in shape ; the orifice is
situated on one side of the median line. The entosolenian tube
is long and attached. A few of the specimens are not nearly so
wide in relation to the height as the one figured. — Locality :
About sixteen at No. 44. It occurs also at several other
stations.
Lagena reniformis sp. nov. var. (PI. 18, fig. 15).
I am treating this as a variation of the above. I believe the
orifice is composed of a series of pores, at any rate it is exceed-
ingly narrow. There are two other tests along with it, in which
the width is about equal to the height, but I think they belong
to the same variety. — Locality : Uncertain.
Lagena reniformis sp. nov. var. spinigera (PI. 18, fig. 16).
The test is compressed, and the two spines, one on either side,
project upwards. The orifice is slightly sunk, and the tube is
long and attached, reaching almost round the shell. Two
specimens only found. — Locality : Nos. 29, 44.
Lagena sp. incerfc. (PI. 18, fig. 17).
Probably this is only L. marginata in a contorted condition.
The test is carinate, compressed and twisted. Two occur. —
Locality : Both at No. 15 ; or one at No. 1 and the other at
No. 15.
Lagena lagenoides Williamson sp. var. (PI. 18, fig. 18).
The test is elongate, not much compressed, and bicarinate.
Aperture fissurine. The keels, which only project slightly, are
tubulated.
I take this to be an elongate variety of L. lagenoides, William-
son sp., pi. 17, fig. 1. Three occur. — Locality : No. 40.
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 205
Lagena staphyllearia Sch wager sp. var. (PI. 18, fig. 19).
Test compressed (lower part angular in outline) with five very
small protuberances arranged, as shown in the drawing, on the
edge of the shell. The entosolenian tube starts straight and
then bends towards the back of the test. Only four occur, and
they vary a little in outline. — Locality : Nos. 3, 11.
Lagena sp. incert. (PI. 18, fig. 21).
I have only made an outline drawing of this form, because I
am not sure what its natural condition may be. The test
is compressed, and nearly all the examples are covered with
shell-growth, which has a sugary appearance. The colour is
a light cream. In those that are partially free from this in-
crustation, the test appears to be more or less in a hispid
condition. The carina, starting at the orifice, often ends abruptly,
as showrn in the illustration, but sometimes it gradually diminishes
until it is lost about half-way down the test. Two or more
spines adorn the base. It may be a compressed form of L. hispida.
—Locality : Nos. 23, 29, 39, 40, 41.
Lagena sp. incert, (PI. 18, fig. 22).
I am puzzled with this form, not knowing whether to treat it
as L. marginata in which the keel has split, thus forming two
long loops, one on either side of the test ; or, as L. auriculata in
which the loops extend almost to the neck. It will be noticed
that the loops are quite separate at the base. Three occur. The
specimens are mixed with those of another form. — Locality : One,
must have been found at No. 43 or No. 44.
? Lagena sp. (PL 18, figs. 23, 24).
I believe this to be a foraminifer, but it is very doubtful if it
be a Lagena. There was a small test, on the same square, which
had every appearance of being the initial chamber of the same
species. Unfortunately, in using a high-power lens for examina-
tion, I accidentally crushed the specimen ; but I bad previously
made an outline drawing of it, see pi. 18, fig. 24.
The large test, pi. 18, fig. 23, is not compressed. The orifice is
a rosette in form, and the upper part of the test is covered with
a raised irregular mesh. Rows of tubular projections run at
206 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
intervals across the test. It being a solitary example I do not
care to make a section of it, but probably it would reveal a series
of chambers. As Mr. Thornhill has placed it among the Lagena,
and it is such an interesting object, I cannot resist the oppor-
tunity of figuring it. It is opaque, but the single-chambered
specimen was quite transparent. — Locality : No. 42.
Lagena maculata sp. nov. (PI. 18, fig. 25).
I was unable, for various reasons, to make out the nature of
this interesting species, so submitted the test to Mr. Earland, and
he has kindly sent me the following description of it :
"The shell appears to consist of two, probably three layers.
An inner test which is covered with a raised hexagonal outline
pattern, like network over a ball, and this in turn is covered
with an extremely thin outer test. This latter may be merely
chitinous or membranous ; it is sufficiently thin to show diffrac-
tion spectra. "Where this outer layer is stretched over the raised
pattern it is depressed in a rounded fashion, as though it had
been pressed down with the tip of the finger into the hexagonal
cavity beneath."
A solitary example. It belongs to the Waterwitch set of
Lagenae. Test not compressed.
Locality : No. 13. Station 238, Lat, 12"44' S., Long. 179*09' W.
(1,050 fms.).
Lagena marginata Walker and Boys var. ventricosa Silvestri.
Lagena ventricosa Silvestri, 1903-1904, Accad. Reale delle Scienze
di Torino, p. 10, figs. 6 a-e.
This seems to me simply a stout form of L. marginata. There
are eleven large specimens, but the carina is carried a little
farther up the test. Three of the tests are nearly round in
section. Examples moderately compressed, with orifice of the
same character, I have placed with L. marginata. — Locality :
Nos. 5, 15.
[Mr. Henry Sidebottom has decided to make a type -slide of the
species described in his two papers as an index to the collection
of Lagenae. The collection will then be presented to the British
Museum (Natural; History), South Kensington, under the title,
<l The Thornhill Collection of Lagenae (South-West Pacific)."
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 207
DESCRIPTION OF PLATES.
Figs.
1-3.
L.
4.
L.
5,6.
L.
7,8.
L.
9,10.
L.
11.
L.
12, 13.
L.
1-1.
L.
15.
L.
16.
L.
17.
L.
18, 19.
L.
20.
L.
21.
L.
22.
L.
23.
L.
24, 25.
L.
26.
L.
27.
L.
28.
L.
29.
L.
30.
L.
31.
L.
32.
L.
Q D
-DO.
L.
Plate 15.
glohosa Montagu sp., x 50
apiculata Reuss sp., x 25
longispina Brady, x 50
botelliformis Brady, x 50
laevis Montagu sp., x 50
aspera Beuss, x 50
aspera Reuss, x 75
rudis Reuss, x 50
hispida Reuss, x 50 .
hispida Reuss var. tuhulata Sidebottom, x 50
striata d'Orbigny sp., x 75 .
costata Williamson sp., x 75
acuticosta Reuss, x 50
hexagona Williamson sp., x 50
hexagona Williamson sp., x 115
hexagona Williamson, sp., compress
X 115
sulcata Walker and Jacob sp., x 50
ph<migera Brady, x 50
semilineata Wright, x 50 .
crenata Parker and Jones, var. x 50
Thomhitti Sidebottom, x 75
stettigera Brady var. eccentrica Sidebottom, x 50
stelligera Brady var. eccentrica Sidebottom, com
pressed variety, x 50 .
foveolata Reuss (?), var. paradoxa Sidebottom, x 75
Hertv:igiana Brady, X 50 .
ed varietv
Page
164
165
165
166
166
167
167
168
168
168
169
170
171
171
171
171
172
173
173
174
174
175
175
177
178
208 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
Plate 16.
Figs.
1. L. splenclida sp. nov., x 75
2, 3. Diagrams of decoration ......
4. L. spumosa Millett, x 75 . . .
5. L. laevigata Reuss sp., x 115
6. L. laevigata Keuss sp. var. virgulata Sidebottom, x 50
7. L. acuta Reuss sp. x 25 . . .
8. L. acuta Keuss sp. var., X 50 .
9. L. lucida Williamson sp., X 50
10-13. L. fasciata Egger sp., X 50
14. L. fasciata Egger sp. var. carinata Sidebottom, X 25
15, 16. L. fasciata Egger sp. var. carinata Sidebottom, x 50
17. L. marginata Walker and Boys, x 50
18. L. marginata Walker and Boys, x 75,
form . . .
19. 20. L. marginata WTalker and Boys, x 75
21. L. compresso-marginata Fornasini, x 75
22. L. marginata Walker and Boys, var.
Chapman, x 25 .
23. 24. L. marginato -perforata Seguenza, x 50
25. L. marginato-perforata Seguenza, x 75
26-28. L. lagenoides Williamson sp., x 50 .
29. L. lagenoides Williamson sp., x 75 .
Trifacial
catenulosa
Page
178
178
179
181
181
182
182'
183
183
184
184
186-
186.
186
187
187
189
189
190
190
HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC. 209'
Plate 17.
Figs.
1. L. lagenoides Williamson sp., x 75 .
2. L. lagenoides Williamson sp. var. nov. duplicate/,, X 75
3. L.formosa Schwager, x 50
4-7. L.formosa Schwager, x 75
8. L. formosa Schwager var., x 75
9. L. Orbignyana Seguenza sp., x 75
10. L. Orbignyana Seguenza sp., x 50
11. L. Orbignyana Seguenza sp., X 75
12. L. Orbignyana Seguenza sp. var. lacunata Burrows
and Holland, x 50
1 3. L. Orbignyana Seguenza sp. var. pulcheUa Brady, X 75
14. L. Orbignyana Seguenza sp.var. clathrata, Brady, x 75
15. L. Orbignyana Seguenza sp. var., x 75
16. 17. L. bicarinata Terquem sp., x 50
18. L. bicarinata Terquem sp., x 75
19. L. bicarinata Terquem sp., x 75
20. L. bicarinata Terquem sp., x 75
21. L. auricidata Brady, x 50
22. L. auricalata Bradv, x 75
Page
190
191
191
191
192
194
194
194
194
195
196
196-
197
197
197
197
198
19&
'210 HENRY SIDEBOTTOM ON LAGENAE OF THE SOUTH-WEST PACIFIC.
Plate 18.
Figs.
1. L. auriculata Brady, x 75
2, 3. L. auriculata Brady var. nov. caudata, x 25 .
4. L. auriculata Brady var. nov. circumcincta, X 115
5. L. auriculata Brady var. nov. clvpeata, x 115.
6. L. auriculata Brady var., x 75
7. L. auriculata Brady var. duplicata Sidebottom, x 25
8. L. auriculata Brady var. duplicata Sidebottom, x 50
9. L. fimbriata Brady, x 75
10. L. fimbriata Brady var. nov. duplicata, x 75
11. L. alveolata Brady, x 50.
12. L. alveolata Brady, x 75
13. L. invaginata sp. nov., x 115 .
14. L. reniformis sp. nov., X 75
15. L. reniformis sp. nov. var., x 75
16. L. reniformis sp. nov. var. spinigera, X 7
17. Lagena sp. incert., x 75 .
18. L. lagenoides Williamson sp. var., x 50
19. L. staphyllearia Sch wager sp. var., x 75
20. L. squamoso-alata Brady, x 75
21. Lagena sp. incert., x 75 .
22. Lagena sp. incert., x 50 .
23. 24. (?) Lagena sp., x 50
2?. L. maculata sp. nov., x 75
Page
198
199
199
199
199
200
200
201
201
202
202
204
204
204
204
204
204
205
193
205
205
205
206
Journ. Quekett Microscopical Club, Scr. 2, Vol. XII., No. 73, Noc mber 1913.
Journ.Q.M.C.
Ser. 2, Vol. XII. PI. IS.
H.Sidebottoni del.ad nat.
West, Newman lith.
Laqenae of the South West Pacific Ocean.
"d
Jour n. O.M.C.
Sep. 2, Vol. XII. PL 16.
A l
6a
V
C
H.Side~bottom del.adn.at.
We s t .Newman
Lagenae of the South West Pacific Ocean.
Joum. Q.M.C.
Ser. 2, Vol. XII, PI. 17.
.
8a
. ?2
■* ;-■;■:. ■■■■^\
■':-V- X--
v
il&K 9
10a
b
Y
Mi
,
. b
[
B
- -
H.StdebottOTn del. ad nat.
West,Newman lith.
Lagenae of the South West Pacific Ocesun.
Journ . Q.M.G.
Ser.2,Vol.XII,P1.18.
jeST?**^.
5a • b
K
10a
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Lagenae of the South West Pacific Ocean.
211
GASTROTRICHA.
By James Murray, F.R.S.E.
Communicated by D. J. Scourjield.
{Bead October 28th, 1913.)
Plate 19.
INTRODUCTION.
I have been reluctant to attempt an introduction to the study
of the Gastrotricha, since my knowledge of the group is by no
means profound, and such as it is has been only recently acquired.
Jt is a group which has now reached such dimensions that it is
desirable there should be in the English language some sort of
synopsis of our present knowledge, and as there appears to be no
one else in the field to supply this want, I shall here do the best
I can.
The main part of this paper is an annotated bibliography,
which I hope will save students much of the trouble I have had.
It is difficult to hit a just mean between giving too much and tco
little. If too comprehensive and not annotated, a bibliography
rather hinders than helps by making the mass of works to be
consulted seem too great. A work is judged by its title to be one
that must be consulted, and after much labour is found to be of
no importance. I had a long search for a new genus and species,
Gastrochaeta ciliata, described by Grimm, before I found that the
name occurred in a mere list, in Russian, without a figure,
and that in a footnote all the comparison made was with species
of Desmoscolex, which belongs to a quite different group of
worms (25).
If the bibliography is too condensed the student is always
liable to suspect that a work omitted from it has not come to the
knowledge of the compiler. Such things frequently happen. ■ I
have here tried to keep a proper balance. All important
212 J. MURRAY ON GASTROTRICHA.
general, biological and systematic works known to me are
included, as well as any really important faunistic studies.
Every work is given in which new species, or supposed new
species, or groups of higher value are described. The systematic
student wants these principally. There are omitted all merely
popular accounts, all trifling faunistic studies (records usually of
doubtful value), all references in textbooks of zoology which
contain nothing fresh, pronouncements on systematic position,
which are mostly only opinions not backed by personal knowledge
of the animals.
Monographists and close students of distribution will require
more than this bibliography contains, but they will be able to
get it for themselves.
It is unfortunate that the Gastrotricha, which include those
old familiar friends of the students of pond life — Chaetonotas
larus and Ichthydium podura — have no popular name. Gosse's
proposed name of " hairy-backed animalcules " is entirely un-
suitable, since some of the genera are not hairy-backed
[Ichthydium, Lepidoderma). I confess I am unable to suggest
any appropriate name. The name suggested by the scientific
term for the whole group, which embodies almost the only
character which they all possess, is unsuitable for popular use_
The Gastrotricha are not animals which can be named off-
hand. The days when we found Chaetonotus larus and
Ichthydium podura, occasionally varied by C. maximus, on all our
pond- life excursions are over. There are a host of Chaetonoti
which have contributed to the records of 0. larus. These species-
are all alike to a casual glance, but are distinguished by minute
characters — the possession of small branches by certain of the
bristles, the form of the minute scales which bear the bristlesr
etc. Some of these are so delicate that a high power and an
oil-immersion lens would be needed for their certain deter-
mination. This is impossible to apply to a living and lively
Chaetonotus, and as to killing the creature merely in order to
find out its name, well — a philosophic naturalist might prefer-
to remain ignorant. To destroy this marvellous little living
gem simply to know how to label it ; is it worth while 1
Now we students of microscopic life cannot pretend to be
squeamish ; we have learned to kill lightly ; every time we clean,
a cover-glass we annihilate a world. But when it comes to»
J. MURRAY ON GASTROTRICHA. 213
deliberately ending the individual life which we have before our
eves, intelligent, and surely innocent, I confess that, old and
hardened as I am at the game, I feel guilty of — murder.
My ideal is that realised by Mr. Bryce, with his " zoo " of
Rotifera, all kept alive in cells, visited again and again for weeks
and months, till they become old familiar friends, each known by
sight and name : where a death in the family is regretted, and
the beasties, in fact, reach a ripeness of old age which must be
rare under natural conditions.
I wish to thank Mr. Rousselet and Mr. Bryce for the assistance
they have given me in preparing this paper, by lending me
specimens and books, and Mr. Harring for bibliographical refer-
ences and extracts from works which I had not seen.
Form axd Structure.
AH Gastrotricha are built on a very uniform plan. Most of
them have a roundish, often 3- or 5-lobed head, a more or less
distinct neck and a slightly expanded body, diminishing pos-
teriorly to a usually forked, but sometimes undivided extremity
{tail or foot). The principal external features are : the tubular
mouth, certain sensory hairs on the head, various forms of scales
and hairs clothing the dorsal surface. The ventral surface is
traversed for its whole length by two bands of vibratile cilia, by
which the creatures can creep in the manner of an Adineta, and
sometimes even, apparently, swim. A few possess clear bodies
which have been supposed to be eyes.
Of the internal structure I shall say little, as I have given it
little study, and I can only quote from authors who have studied
it. The animals are on about the same plane as the Rotifera for
•complexit}', but they look much simpler — fewer organs are readily
visible. A casual examination shows only a thick skin and the
body cavity, through which passes the simple alimentary canal ;
the slender oesophagus passing through an oblong muscular
pharynx ; the expanded stomach (or intestine) occupying most
of the body cavity. There is a small intestine, from which the
anus opens at the base of the furea, on the dorsal side.
Several naturalists have detected a water-vascular system
somewhat like that of the Rotifera, but according to Zelinka
it differs in many points. The canals are much convoluted,
214 J. MURRAY ON GASTROTRICHA.
and possess only one vibrating cell corresponding to the series-
of flame-cells of Rotifera ; there is no contractile vesicle, and the
canals open independently on the ventral side and have no
connection with the intestine.
While the eggs are frequently conspicuous, and their develop-
ment may be conveniently studied, the sexual system is little
known. Zelinka distinguishes paired ovaries. If the supposed
male organs are such the Gastrotricha are hermaphrodite.
Zelinka recognises in the alimentary canal the following parts :
mouth, oesophagus, stomach, intestine with rectum and anus.
There is a well-developed muscular system, and the brain and
nervous system are similar to those of the Rotifera.
Haunts and Habits.
The Gastrotricha are found mainly in ponds, oftenest among
the bottom sediment or vegetation. They rarely occur on mosses,
except the permanently moist aquatic kinds. A few (at least
one species, C. marinus) live in the sea.
They are much less common, even in ponds, than the
Rotifers and Water-bears. You cannot go out to collect
assured of getting some — you must trust to casual occurrences
when studying other things.
There are no special methods of collecting them. They will
occur among your Rotifers, but not if you collect in clear, open
water. Perhaps the likeliest means to obtain some is to wash
aquatic weeds — Myriophyllum, Fontinalis, Lemna, etc.
If you wish to preserve them it can easily be done. As they
are not contractile, they can be killed without previously
narcotising by osmic acid, when they retain the natural shape..
They can be mounted in fluid cells by Rousselet's method, but
formalin of the strength used for Rotifers is not a suitable
medium, as it produces subsequent distortion. Some better
medium has yet to be found.
They appear to have only one habit, that of eating. They
ar; always in motion, some slowly, some quickly, and always
seem to be nosing for food. Yet they are not greedy eaters, but
pick daintily here and there. As they creep along over the weeds
they give the impression of active intelligence proportioned to-
their needs.
j. murray on gastrotricha. 21£>
Historical Sketch.
As a history would be little more than the bibliography
arranged chronologically, it need not take up much space.
So far as my knowledge goes, the first notice of an animal of
this order is by Joblot (32) 1718, who figures (Plate 10, fig. 22)
his " poisson a la tete en trefie," which is the animal now known
as Ichthydium.
Corti 1774 (10) speaks of an " animaluzzo molle," and figures
it, which Ehrenberg thinks may be a Chaetonotus.
Eichhorn 1781 (20) figures (Plate 2, fig. R) what may have
been a Chaetonotus.
These were the pioneers, who bestowed no binomial desig-
nations, but, before either Eichhorn or Corti, Miiller had in 1773
(42) given three such names, the first, Cercaria podura, still
persisting as Ichthydium podura.
Many of the pre-Ehrenbergians bestowed various names on
Gastrotrichs, usually only in attempts to classify, not describing
supposed new species : Schrank 1776 (53) Brachionvs pilosus ;
Lamarck 1815 (34) Furcocerca ; Bory 1824 (3) Leucophra, 1826
(4) Diceratella ; Ehrenberg's first attempt, Hemprich and Ehren-
berg 1828 (29) was Diurella podura (= Ichthydium).
Ehrenberg did not notably advance the knowledge of this
order, but he described two new species besides others, which are
not now recognised as Gastrotrichs.
After Ehrenberg came a rather barren period leading on to
quite modern times: Dujardin 1841 (16), Gosse 1851 (23) and
1864 (24), Schultze 1853 (55), Schmarda 1861 (52), Metchnikoff
1865 (41), Tatem 1867 (61). The only works of any importance
in this period are Gosse's and Metchnikoff's.
Modern times may be said to begin with Daday in 1882 (11),
and the principal workers have been Daday 1897 (12), 1905 (14),
1910 (15); Collin 1897 (8), 1912 (9); Stokes 1887 (57) (59);
Zelinka 1889 (71); Voigt 1904 (68); Lauterborn 1893 (35);
Griinspan 1908 (26); Marcolengo (40) (72).
Classification.
The classification of the Gastrotricha is in an unsatisfactory
condition. They are difficult animals to classify. I sympathise-
with the efforts authors have made to introduce order into the-
216 J. MURRAY ON GASTROTRICHA.
group, and will not attempt to modify the generic arrangement,
beyond shifting about some of the species. I am not qualified to
deal with the question, but as some little assistance to students
1 shall point out some apparent shortcomings of the prevailing
classification.
The three fork-tailed genera, Ichthydium, Chaetonotus and
Lepidoderma, are separated on very slight characters, as Stokes
(57) recognised in " lumping " them all together. Ichthydium
has neither plates nor dorsal bristles ; Lepidoderma has scales,
but is supposed to have no bristles ; Chaetonotus has bristles,
and may have scales. So if an Ichthydium or a Lepidoderma
possesses any dorsal bristles it becomes a Chaetonotus. How
many bristles are necessary ? Some so-called Lepidoderma have
a very few bristles. L. loricatus, Stokes, has no bristles, while
a variety has four near the tail.
Authors have made the matter worse by entirely disregarding
the generic definitions, even those made by themselves. Thus
Zelinka's Lepidoderma was instituted first to contain Dujardin's
C. squammatus, which was described in these terms, " Revetu
en dessus de poils courts, elargis en maniere d'ecailles pointues
regulierement imbriquees," and which is thus a true Chaetonotus,
following Zelinka's own definition.
The possession or not of scaly armour is surely itself more
important than the presence or not of bristles on the scales,
but the character has not been used in classification quite
rightly, for the scales are after all only the enlarged bases of
the hairs, and there is every gradation from a slightly enlarged
insertion to large imbricated scales.
Authors have further confused matters by professing to identify
a,s the species of the earlier authors animals which are quite
different from their descriptions and figures. This is pernicious,
as the practice nullifies the meaning of language, however
precisely used. It may be admitted that the descriptions of
Muller and Ehrenberg are insufficient to distinguish their species
from the numerous similar species now recognised. But the
species must either be dropped as " insufficiently described," or,
if we profess to recognise them, it must be in animals possessing
at least the characters ascribed to them by their discoverers.
Ehrenberg has many faults, among which I reckon not
least the insufficiency of his descriptions. Frequently these
J. MURRAY ON GASTROTRICHA. 217
contain no single distinctive character, and if it were not for
his figures their recognition would be impossible. But he was
not a slipshod observer, and when he happens to mention a
distinctive feature I have no doubt the animal observed possessed
it. Thus when he distinguishes C. maximus from C. larus by
its dorsal bristles of equal length, we must give him the credit
of supposing that his animal looked like that, unless naturalists
agree that no such animal exists — a difficult thing to prove.
There are species with the dorsal bristles approximately of equal
length, and so Gosse is not justified in identifying as C. maximus
a species having the posterior bristles much longer.
In the separation into larger groups, sub-orders, or families,
the group has been equally unfortunate. The classification by
Fraulein Griinspan (26) recognises three sub-orders :
Suborder I. Euwhthtdina, having a forked tail.
II. Pseudopodisa, having an apparently forked tail.
III. Apodixa, without a forked tail.
55
55
I am unable to grasp the distinction between a forked tail and
an apparently forked tail, and the Apodina include one genus
(Stylochaeta) which has a forked tail ; minute certainly, but is a
small tail not a tail ?
Zelinka's (71) classification is consistent, but the more puzzling
genera were not discovered when he wrote. He recognises two
sub-orders, and, I should suppose, three families, though he only
names two :
I. Sub-order : Euichthydina, having a "furca."
1. Family Ichthydidae, without bristles.
Genera Ichthydiu'ni and Lepidoderma.
2. Family Chaetonotidae, with bristles.
Genera Chaetonotus and Chaetura,
II. Sub-order: Apodina, without a "furca."
Genera Dasydytes and Gossea.
Collin (9) follows Zelinka's classification, naming the family
Dasydytidae, which includes all the Apodina, and allocating
all the genera described since Zelinka's work to places in the
three families.
All this is very unsatisfactory. The anomalies of these systems
I have pointed out as exemplified in that of Fraulein Griinspan.
Journ. Q. M. C., Series II.— No. 73. 15
218 J. MURRAY ON GASTROTRICHA.
I have no better to offer, so I suggest that we leave classification
on broad lines till we know more, and classify in genera only.
These have also been badly handled. Ehrenberg's two genera,
Ichthydium and Chaetonotus, will serve as a beginning of classi-
fication till we find something better. The distinction between
hairy and smooth is not important, and in many genera of
animals both types occur — -e.g. Macrobiotus among Tardigrada,
but among Gastrotricha, if we are to have divisions at all,
we must be satisfied with very trivial characters. Miiller's
Cercaria poduva, which became the type of Ichthydium, was
probably a composite diagnosis, as some of his figures show
bristles. I have shown the unsatisfactory treatment of his genus
Lepidoderma by Zelinka, but, if his generic characters were
regarded in allotting species to it, it might serve as a temporary
artificial genus till we see our way out of the muddle.
Ehrenberg's obsession for symmetry in classification led to
many obviously false associations of species, and tyrannised over
naturalists till a late period, even as late as 1864 affecting
Gosse. It is curious now to regard the genera once included
in the Gastrotricha — Ptygura, Glenojihora — and to think that
Sacculus and Taphrocampa were originally described by Gosse
as Gastrotrichs.
Key to the Genera.
A. Without a furca.
1. Body with long bristles .... Dasydytes.
2. Body without long bristles . Anacanthoderma.
3. Head with antennae . Gossea (G. antennigera).
B. Furca minute or obscure.
4. Furca minute, large barbed bristles . Stylochaeta.
5. Furca obscure, short ..... Setopus.
6. Head with antennae . . . Gossea (two species).
C. Furca conspicuous, body with bristles.
7. Furca simple, bristles pointed . . Chaetonotus.
8. Furca simple, bristles expanded at apex Aspidiophorus.
9. Furca twice furcate ..... Chaetura.
D. Furca conspicuous, body without bristles.
10. Body with scaly armour . . . Lepidoderma.
11. Body without scales .... Ichthydium.
J. MURRAY ON GASTROTRICHA. 219
Note. — Anacanthoderma can hardly be separated from Dasy-
dytes, as the only species is described as having some bristles.
Aspidiophorus is a Chaetonotus, having the bristles enlarged at the
apex, scarcely a generic distinction, as those having enlarged
bases are not considered generically distinct. Gossea is usually
put in the Apodina, but Daday's two species possess the furca,
and Gosse's antenniger with its caudal bundles of setae may be
said to possess the homologue of the furca. Setopus primus
is scarcely distinguishable, even as a species, from Dasydytes
bisetosus Thomp., yet from the possession of a slight medial
depression at the posterior end it has technically a furca, and
becomes a distinct genus.
List of all Species which have been Described.
In alphabetical order, and under the original generic names,
with critical notes on synonymy and specific values.
1910. Anacanthoderma punctatum Marcolongo (40).
1902. A sp)idonotus paradoxus Yoigt. (65). Now a genus Aspidio-
phorus.
1865. Cephalidium longisetosum Met. (41). Is a Dasydytes.
1773. Cercaria podura Mull. (42). Now the type of Ichthydium
Ehr.
1887. Chaetonotus acanthodes Stokes (57).
1887. C. acanthophorus Stokes (57).
1903. C. arquatus Voigt. (67).
1832. C. breve Ehr. (16).
1889. C. brevispinosus Zel. (71).
1901. C. chuni Voigt. (64).
1887. C. concinnus Stokes (57). Is a Lejndoderma.
1910. C. decemsetosus Marco. (40).
1905. C. dubius Dad. (14).
1887. C. enormis Stokes (57).
1905. C. erinaceus Dad. (14).
1887. C.formosus Stokes (59).
18(54. C. gracilis Gosse (24).
1905. C. heterochaetus Dad. (14).
1910. C. hirsutus Marco. (40).
1865. C. hystrix Met. (41).
220 J. MURRAY ON GASTROTRICHA.
1910. G. larvides Marco. (40).
1902. C. linguaeformis Voigt. (66).
1867. G. longicaudatus Tatem (61). Is an Ichthydium.
1887. G. longisjnnosus Stokes (57).
1887. G. loricatus Stokes (57). Is a Lepidoderma.
1893. G. macracanthus Laut. (35). Is probably G. entzii
(Dad.).
1889. C. macrochaetus Zel. (71).
1904. G. mwrinus Giard. (22).
1832. G. maximus Ehr. (18). 1
1910. G. minimus Marco. (40).
1908. C. multispinosus Griin (26). Is C. tabnlatum Schm.
1901. G. nodicaudus Voigt. (63). Very like G. entzii (Dad.).
1910. C. nodifurca Marco. (40). Very like G. entzii (Dad.).
1887. G. octonarius Stokes (57).
1897. G. ornatus Dad. (12).
1910. C. paucisetosus Marco. (40).
1889. C. persetosus Zel. (71). j
1909. C. ploenensis Voigt. (69).
1905. C.pusillus Dad. (14). ]
1887. C. rhomboides Stokes (57). Is probably 0. entzii (Dad.).
1865. C. schidtzei Met. (41).
1901. C. serraticaudus Voigt. (63).
1889. C. similis Zel. (71). |
1909. C. simrothi Voigt- (69).
1887. C. spinifer Stokes (57). ]
1887. C. spinidosus Stokes (57).
1864. C. slackiae Gosse (24).
1841. C. squammatus Dnj. (16).
1902. C. snccinctus Voigt. (66).
1887. C. sulcatus Stokes (57). Is an Ichthydium.
1908. C. tenuis Griin. (26).
1902. C. uncinus Voigt. (66).
1908. C. zelinhai Griin. (26),
1865. Chaetura capricornia Met. (41).
1913. C. piscator Murray. (Described in this paper for first
time.)
1851. Dasydytes antenniger Gosse (23). Now the genus Gossea.
1891. D. bisetosus Thomp. (62).
i909. D. dubiiis Voigt. (69).
J. MURRAY ON GASTROTRICIIA. 221
1909. B.festhians Yoigt. (69).
1851. D. goniathrix Gosse (23).
1909. D. ornatus Voigt. (69).
1910. D. pa ucisetosus Marco. (40).
1887. D. saltitans Stokes (59).
1901. D, stylifer Yoigt. (64). Is a Stylochaeta.
1893. D. zelinkai Laut. (35). Seems to be D. goniathrix Gosse.
1886. Ichthydium bogdanovii Schim. (51). Is a Chaetonotus.
1905. /. crassum Dad. (14).
1908. /. cyclocephalum Griin. (26).
1882. /. entzii Dad. (11). Is a Chaetonotus.
1901. I.forcipatum Voigt. (64).
1861. I . jamaicense Schin. (52). Is a Chaetonotus.
1897. /. macrurum Collin. (8).
1865. /. ocellatum Met. (41).
1861. /. tabulatum Schm. (52). Is a Chaetonotus.
1908. /. tergestinum Griin. (26).
1905. Gossea fasciculata Dad. (14).
1905. G. pauciseta Dad. (14).
1897. Lepidoderma biroi Dad. (12). Is probably C. entzii (Dad.).
1905. L. elongatum Dad. (14). Is probably C. entzii (Dad.).
1910. L. hystrix Dad. (15). Is probably C. entzii (Dad.).
1890. Polyarthrafusiformis Spencer (56). Now genus Stylochaeta.
1908. Setopus primus Griin. (26). Scarcely differs from Dasydytes.
1776. Trichoda larus Mull. (43). Now Chaetonotus larus.
Identification of Species.
It was my ambition to accompany this paper by a key to all
the species hitherto described, so that the student might identify
them all, or at least know what characters they were supposed
to have. I found the task beyond my powers, for not only are
there a number of descriptions which I have been unable to
consult, but many of the diagnoses are such that to make use
of the characters given in them would be actually misleading.
This is especially true of negative characters. Certain species
are described as having the body covered with scales, others as
having some or all of the bristles barbed or with supplementary
points. It must not be assumed that species not thus character-
ised do not possess those characters. Both are structures
222 J. MURRAY ON GASTROTRICHA.
excessively difficult to see, and the authors of species may have
overlooked them.
There is no more definite character for distinguishing species
of Chaetonotus than the form of the dorsal plates, if one could
only see them, but nothing has astonished me more than the
utter invisibility of those plates, till some accident, such as finding
an empty skin or mutilated specimen, has revealed them.
As I have put some work into the preparation of this key, and
do not wish to throw it away, I have made some use of the
material by indicating for the genus Chaetonotus certain groups
of species characterised by the possession of some common
feature.
Chaetonotus.
Body covered by Plates or Scales.
G. acanthodes, acanthophorus, arquatus, brevispinosits, chuni,
entzii, erinaceus, heterochaetus, hystrix, larus, linguaeformis, macro-
chaetus, maximus, octonarius, ornatus, persetosus, ploenensis,
pusillus, schultzei, serraticaudits, similis, simrothi, spinifer, squam-
matus, succinctus, tabidatus, tenuis, uncinus, zelinkai.
Stated to have no Plates.
G. enormis, formosus.
Nothing said about Plates.
G. bogdanovii, dubius, gracilis, jamaicense, longispinosus,
marinus, slackiae, spi?iulosus.
With Cephalic Shield.
C. entzii, erinaceus, formosus, maximus, ornatus, persetosus,
pusillus, schultzei, tenuis, zelinkai. Not noted for the other
species.
Head not Lobed.
G. bogdanovii, dubius, jamaicense, marinus, ornatus, slackiae,
tabidatus.
Head Three-lobed.
G. brevispinosits, chuni, erinaceus, formosus, heterochaetus,
hystrix, larus, linquaeformis, macrochaetus, pusillus, schultzei,
serraticaudus.
j. murray on gastrotricha. 223
Head Five-lobed.
C. acanthophorus, arquatus, eno?"mis, gracilis, longispinosus,
maximus, octonarius, persetosus, ploenensis, similis, simrothi,
spinulosus, squammatus, succinclus, tenuis, uncinus, zelinkai.
All Bristles with Supplementary Points (Barbs).
C. chuni, erinaceus, hystrix, schultzei, similis, spinifer.
Some Bristles Barbed.
C. acanthophorus, enormis, heterochaetus, longispinosus, macro-
chaetus, octonarius, persetosus, spinulosus, zelinkai. All the
others are supposed to have simple unbranchecl bristles.
Having Series of Larger Thicker Bristles.
C. acanthodes, acanthophorus, bogdanovii, brevispinosus, dubius,
enormis, heterochaetus, longispinosus, macrochaetus, octonarius,
ornatus, ploenensis, persetosus, similis, spinifer, spinulosus, suc-
cinctus, tenuis, uncinus, zelinkai.
Posterior Bristles Progressively Longer (exclusive of
the larger bristles above noted).
C. arquatus, chuni, entzii, erinaceus, hystrix, larus, macro-
chaetus, ornatus, pusillus, schultzei, similis, tenuis, zelinkai.
Bristles equal or not Noticeably Longer Posteriorly.
C. brevispfinosus, dubius, formosus, gracilis, heterochaetus,
jamaicense, linquaeformis, marinus, maximus, serraticaudus, sim-
rothi, slackiae, squammatus, tabulatus.
Notes on Some Species I have Seen.
I have in some of my faunistic lists noted Chaetonotus larus
and Ichthydium podura, but these records have the same value
as nearly all such records — i.e. none.
At various times I have made studies of species which I could
not identify with the assistance of the literature at my disposal.
After reviewing nearly all the literature, and taking all tha
224 J. MURRAY ON GASTROTRICHA.
diagnoses at their face value, it appears that several of these
species differ from any of those described in the works known
to me.
I would have dealt with these in the usual way and described
them as new species, but just as I was finishing this paper Mr.
Harring of Washington was good enough to call my attention
to a paper by Marcolongo which I had overlooked (40). In that
paper there are described a number of new species of Chaetonotus,
as well as a new family and genus.
Mr. Harring has kindly transcribed the descriptions, which
appear to be better than such things usually are, but as they
are unaccompanied by figures no certain identification is possible.
I consider all descriptions of animals in this group unaccompanied
by figures as insufficient, but we are promised figures in a forth-
coming work by the same author.
In the circumstances I have no alternative but to withdraw
my new species in the meantime, but there can be no harm in
figuring and describing them as animals I have actually seen.
Several of these are figured on the plate, in company with
others which I do nob suppose to be new species.
The species of Chaetura I can describe with an easy mind, as
no one since Metchnikoff has ever described a species of this
genus.
Ichthydium sp. (PL 19, fig. 23).
A graceful little animal, with very slender neck, deeply
trefoliate head and long furca. The branches of the furca
are close together at the base, and diverge, tapering to points.
No tactile setae are noted, but the animal probably had them.
Length about 130 fx.
Habitat. — Amongst Sphaynum, Fort Augustus, Scotland, 1904.
It is a good deal like Joblot's " poisson a la tete faite en trefle,"
which some have identified as /. podura. But what was /. podura
like ? Various animals have been figured by authors under that
name, stout animals and thin animals, with long, slender furca
or with little blunt knobs. Usually they do not appear to have
gone back to Miiller, or even to Ehrenberg, to find what podura
was like. If they had they would have found it was like various
things. Miiller's podura possessed bristles (in some figures), and
J. MURRAY ON GASTROTRICHA. 225
so ought to go into Ehrenberg's genus Chaetonotus. Its furca
was somewhat like the animal I have figured. Ehrenberg's had
a different furca.
Lepidoderma sp. (PI. 10, fig. 29).
A very small animal, with five-lobed head, apparently
rhomboid scales, and a short furca with diverging branches.
Long, tactile setae on the head. Length, 50 to 60 /x.
The small size might lead to the supposition that the animal
is young. In the only instance in which I have seen a Gastrotrich
hatch out of the egg the young was of the full adult length of
the species. It had only to eat and fill out. From this I suppose
that Gastrotricha, like many Rotifera, do not grow appreciably
in length.
I say the scales are " apparently ' rhomboid, because the
regular double diagonal arrangement in rows might give rise
to this appearance although the scales were of some other
form.
Chaetonotus sp. (PI. 19, figs. SlaSlb).
Of medium size ; trunk oval, neck well marked, head slightly
elongated, five-lobed, without cephalic shield. Mouth nearly
terminal, with tuft of hairs.
The bristles on the head and neck are excessively short and
fine. At the front of the trunk they become abruptly longer
and thicker (though still short) and progressively longer
posteriorly. Near the base of the furca there are some half-
dozen bristles longer and thicker than any others. None of the
bristles are barbed.
The scales from which the hairs spring are elongate hexagons,
with the angles so rounded off that they are almost oval. They
are arranged in regular diagonal rows, and are separated at
their bases by spaces about equal to the width of the scales.
The furca is short, the branches diverging, then converging
(enclosing a rhomboid place), obtuse.
No plates can be seen on the head or neck. It is the only
species I have seen in which the scales are visible and conspicuous
in a specimen in good condition.
Habitat. — Scotland.
226 J. MURRAY ON GASTROTRICHA.
t
Chaetonotus entzii (Dad.)? (11) (PL 19, fig. 26).
A large animal, 250 to 300 jul and upwards in length. Head
obscurely 3-lobed, with two anterior processes, and two others at
posterior angles. Body long, nearly parallel-sided, covered with
apparently rhomboid scales, in diagonal rows, and fine short hairs,
gradually becoming longer posteriorly. Furca very long, nodose
(about twenty nodes in the length), widely divergent at base where
separated by small sulcus, less widely divergent above base.
Habitat. — Pond in the Praca Republica, Rio de Janeiro, Brazil ;
several specimens.
About eight species of long-furcate nodose Gastrotrichs have
been described, which have all a suspiciously strong family likeness.
Some of these are certainly synonymous, their authors being
unaware of the existence of the other species. Daday, who is
responsible for the greater number of them, professes to draw
distinctions, but he is not very convincing, and moreover I have
found the animal here described to be extremely variable.
Daday first described entzii as an Ichthydium, although it had
the characters of Chaetonotus. Later he described similar forms
as Lepidoderma, although some of them at any rate did not fit his
genus. Some he compared with entzii and with rhomboides Stokes,
noting that some had not the spines on the head, some had the
furca hairy, others smooth, etc. I cannot pretend to sort oat all
of these here, but content myself with pointing out the family
resemblance.
Those I found in Rio had the hairs extremely variable, in some
very short, in others not visible at all. I could not doubt that
these were all one species, as I could see no other differences
whatever. The various species having long nodose furca will be
found noted in the list of all described species.
Chaetonotus sp. (PI. 19, fig. 30).
Large. Head short, 5-lobed, with cephalic shield, neck slightly
marked. Body clothed with simple hairs in about fifteen or
sixteen longitudinal rows, progressively longer posteriorly. Scales
like spear-heads, very like those of C. larus (fig. 9). The outline
of the body appears crenulate, with very prominent papillae in
the narrow part above the furca. About eight longer setae close
J. MURRAY ON GASTROTRICHA . 227
to the furca, springing from the papillae. Fnrca longish, widely
divergent, obtuse pointed.
Habitat. — Praca Republica, Rio de Janeiro. The original larus
is probably not now recognisable, but modern authors have
defined it as an animal with scales as in fig. 9, and about eleven
longitudinal rows of them. This has more numerous rows. As
far as can be judged from the description without a figure, this
species is very like C. laroides Marco., but that is said to have the
scales truncate posteriorly.
It is to be noticed that these very destinctive scales are quite
invisible in living or well-preserved specimens. I have only
managed to see them in empty, partly shrivelled skins.
Chaetonotus sp. (PI. 19, fig. 34).
Of moderate size. Head obscurely 3-lobed, with large cephalic
shield. Body covered with long, widely out-curved bristles, all
barbed, in few rows (six seen in dorsal view) springing from
obscure but large hemispherical scales. Close to the furca nine
very long, recurved, barbed bristles, three dorsal, six lateral.
Branches of furca long, separated by sulcus at base, outcurved,
knobbed.
Habitat. — Sydney and New Zealand ; a very similar form in
Rio, Brazil.
The most obvious character is the widely spreading bristles.
Even those nearest the cephalic shield are long, but they are
progressively longer posteriorly till near the furca, when a few
quite short bristles intervene between the longest dorsal bristles
and the special large ones at the furca.
Chaetonotus sp. (PI. 19, fig. 35).
Of moderate size, relatively broad and squat. Head rounded,
5-lobed. Neck well-marked, short. Trunk parallel-sided. Body
covered with apparently rhomboid scales, each bearing a short
spine or scale. Furca short, diverging, then converging (enclosing
a rhomboid space), the basal portion scaly, the apical portion
smooth. There are long tactile setae on the head.
The general form is like that of Ichthydium ocellatum Met.
[Lepidodei'ma ocellatum Zel.). I saw nothing like the eye-spots
ascribed to both those animals.
228 J. MURRAY ON GASTROTRICHA.
As there are no type specimens, and only MetchnikofTs descrip-
tion to go by, there is no justification for transferring his species
to the genus Lepidoderma, as Zelinka does. It is either an
Ichthydium Ehr. or insufficiently described and unrecognisable.
Zelinka's animal may be the one which I here figure. If so
it seems to me that the little triangular scales or spines are
homologous with the bristles of Chaetonotus, and not with the
scales of Lepidoderma, and so it should be placed in the former
genus.
Habitat. — Summit of Ben Lawers, Scotland, among moss, 1905.
Chaetura piscator sp. now (PI. 19, fig. 33).
Specific characters. — Small ; head elongate, egg-shaped, fringed
with long setae ; neck moderately constricted ; body spindle-
shaped ; each branch of furca forked, branches equal ; trunk
bearing at least four longitudinal series of fine bristles shaped like
fish-hooks, and some straight setae near the furca.
General description. — Length 150 /x, head 50 /x long by 36 /x
wide, trunk 30 fx wide, branches of furca about 12 jx ; hooks
project about 15 fx above the surface.
The head is the widest part of the body. It is fringed by long
straight hairs or setae, and bears some larger movable setae which
appear to have a tactile function. The neck is slightly constricted,
but has a swelling. The dorsal hairs are shaped exactly like fish-
hooks, without their barbs. They spring out at nearly right
angles to the skin, curve round in the posterior direction, and
nearly touch the skin at their tips. I distinguished four rows
of them, but in dealing with such excessively fine structures
it is not well to state hard-and-fast numbers. Four of the
straight setae could be seen dorsally, close by the tail ; the four
branches of the furca are nearly equal, slightly curved, and have
blunt tips.
Technically this is a Chaetura, having the branches of the furca
furcate, although in MetchnikofTs type species, G. capricornia,
they are not properly furcate, but bear little branches on the
inner side. As in the type, the head is broader than the trunk
and there are stiff bristles over the tail. The fishhook-like setae
distinguish it from all other known Gastrotrichs.
Habitat. — Amongst moss, Shetland Islands, 1906.
j. murray on gastrotricha. 229
Bibliography.
An asterisk * indicates works in which new species are described.
The works of any importance number scarcely more than a
dozen. They are Ehrenberg, 1838 (19); Gosse 1851 (23), and
1864 (24); Metcbnikoff 1865 (41); Stokes 1887 (57); Daday
1882 (11), 1901 (13), 1905 (14), 1910 (15); Zelinka 1889 (71);
Giard 1904 (22); Yoigt 1904 (68); Griinspan 1909 (26); Collin
1912 (9).
With these works the student will have everything he requires,
except a few descriptions of doubtful new species.
Ehrenberg, 1838, summarises the work of the pioneers, and
originates a classification. Fraulein Griinspan, 1909, gives the
fullest systematic account of the group. Zelinka, 1889, is far and
away the best work on the subject, being a painstaking and
minute study ; but much has been added to our knowledge since his
memoir appeared. Collin, 1912, is simply a compilation, but a
useful one. The others noted above are the principal systematic
works, containing descriptions of many species.
1. Archer, W. In Quart. Joum. Micr. ScL, 14, p. 106, 1874.
Exhibited at Dubl. Micr. Club, C. maximus, C. gracilis,
and D. antenniyer ; all found in Ireland. Note that the
last species can elevate and depress its antennae.
2. Barrois, T. Comptes rendus, July 1887. Trans, in Ann.
Mag. Nat. Hist., xx., p. 365, 1877.
A segmental worm, having the appearance of Ichthy-
dium, but differing much in structure. Probably related
to Hemidasys, Turbanella, Zelinkia, Philocyrtis, which are
not Gastrotricha.
3. Bory de St. Vincent. Encycl. method., Paris, 1824.
Furcocerca podura ( = Ichthydium) ; Zeucophrya larus
( = Chaetonotus).
4. Ibid. Essai des micr., 1826.
Diceratella larus ( = Chaeto?iotus).
5. Bryce, D. In letter to Fraulein Griinspan (vide 26, p. 228).
Records C. zelinkai for England and Scotland.
6. Butschli, O. Freilebende Nematoden u. d. Gattung Chae-
tonotus. Zeit. fur wiss. Zool., 26, pp. 385, 390, etc., 1876.
Classification and Anatomy. Good structural figures of
C. maximus and C. larus.
230 J. MURRAY ON GASTROTRICHA.
7. Claparede, E. Misc. zool. III. nouveau genre de Gastero-
triches. Ann. Sci. Nat., Ser. 5, vol. 8, p. 18, 1867.
Hemidasys agaso gen. et sp. nov. Not a Gastrotrich, I
think.
*8. Collin, A. Rot. Gastro u. Entoz. Deutsch Ost-Afrika, 4, p. 9,
1897.
/. macrurum sp. n. A somewhat meagre description,
from figure drawn by Stuhlman.
9. Ibid. Gastrotricha. In Susswasserfauna Deutschlands,
pp. 240-65, figs. 475-507.
A good account of thirty-two German species, with
many useful figures. No new species.
10. Corti. Osser. micr. sulla Tremetta, p. 89, PI. 2, 1774.
Ehrenberg thirks the " animaluzzo molle " may have
been C. maximus. I have not seen the work.
*11. Daday, E. Ichthydium entzii.
Termes. Fiiz., pp. 231-52, PI. 3, 1882.
New species ; full description and good figures. Seems
to be the first appearance of a much-described animal
which is almost certainly the same as Stokes' C. rhom-
boides, and is probably also Yoigt's C. nodicaudus
and Daday's own L. hystrix, L. elongatum and L. biroi,
as well as C. macracanthus Laut. I found the animal
in Rio de Janeiro, and noted that the dorsal hairs
vary greatly in length and may be absent, so that
the species is both Chaetonotus and Lepidoderma on
occasion !
*12. Ibid. Uj-Guineai Rotatoriak. Math. es. Termes. Ertes.,
vol. 15, pp. 145-48. (In Hungarian.) 1897.
New species — C. orno.tus and L. biroi.
13. Ibid. Mikr. Siisswasserthiere aus Deutsch Neu-Guinea.
Termes. Filz., 24, 56 pp., 3 plates, 1901.
Description and figures of the two new species of his
previous paper (1897).
*14. Ibid. Susswasser-mikrofauna Paraguays. Zoologica, 18,
pp. 72-86, Pis. 5-6, 1905.
Eight new species — I.crassum, L. elongatum, C.pusillus,
C. dubius, C. erinaceus, C. heterochaetus, G. fasciculata,
G. paaciseta.
J. MURRAY ON GASTROTRICHA. 231
*15. Ibid. Susswasser-mikrofauna Deutsch Ost-Afrikas. Zoo-
logica, 23, pp. 56-9, PI. 3, 1910.
New species — L. hystrix.
*16. Dujardin, F. Hist. nat. des Zoophytes Infusoires, pp. 515-
69, PL 18, figs. 7-8, 1841.
New species — C. squamniatus.
17. Ibid. Sur un petit animal marin (l'Echinodere). Ann. Sci.
Nat., Ser. 3, vol. 15, p. 158, PI. 3, 1851.
Once classed with the Gastrotricha.
*18. Ehrenberg, C. J. Organ, in d. Richtuny d. kleinsten Raumes,
2nd Part, Berlin, 1832.
Descriptions (perhaps not his earliest) of /. podura,
C. maximus, C. larus, C. breve.
19. Ibid. Die Infusionsthierchen, pp. 386-90, 1838.
Redescribes the same four species as in 1832.
20. Eichhorx, I. C. Naturgeschichte der kleinsten Wasserthiere,
p. 35, PI. 2, fig. r, 1781.
Probably a Chaetonotus.
21. Florentin, R. Faune des mers salees. Ann. Sci. Nat.
(Ser. 8), 10, p. 272, 1899.
Records Lepidoderma ocellatam from salt water.
*22. Giard, A. Faunule caracteristique des sables a Diatomees.
C. R. Soc. Biol, pp. 1061-5, 1904.
New species — C. marinus. Also new genera Zelinkia
(sp. Z. plana) and Philocyrtis (sp. P. monotoides), which
are very doubtful Gastrotricha.
*23. Gosse, P. H. A Catalogue of Potifera found in Britain.
Ann. Mag. Nat. Hist., Ser. 2, vol. 8, p. 198, 1851.
New genus Dasydytes, and new species D. goniathrix
and D. antenniger ; no figures. Saccidus viridis described
as a Gastrotrich.
*24. Ibid. The hairy-backed Animalcnli. Intell. Obs., V.,
pp. 387-406, 2 plates, 1864.
New species — C. slackiae, C. gracilis.
Taphrocampa new genus, described as a Gastrotrich.
25. Grimm, O. A. Fauna im baltischen Meere (is a German
rendering of the Russian title). Arb. d. St. Peter. Naff
Ges., 8, p. 107, 1877.
Gastrochaeta ciliata new genus and species. No figure
given. In a footnote he compares the animal with various
232 J. MURRAY ON GASTROTRICHA.
species of Desmoscolex, so it is probably not a true
Gastrotrich.
*26. Grunspan, Therese. Systematik cler Gastrotrichen. Zool.
Jahrb., pp. 214-56, 1908.
A comprehensive synopsis of all known species. Seventy
admitted species ; six new species and a new genus — /. terges-
tinum, I. cyclocephalum, C. zelinkai (and var. gra.censis), C.
tenuis, C. midtispinosas, Setoptcs primus(gen. et sp. nov.).
27. Ibid. Die SUsswasser-Gastro-trichen Europas. Eine zusam-
menfassende Darstellung ihrer Anatomie, Biologie und Sys-
tematik. Ann. Biol. Lacustre, Bruxelles, vol. 4, pp. 21 1— 365?
61 figs.
28. Hartog, M. Rotifera Gastrotricha and Kinorhynchia.
Cambridge Nat. Hist., vol. 2, p. 232, etc., 1896.
A good account and figures of seven known species.
29. Heinrich u. Ehrenberg. Symbolae physicae. Evertebrata.
I. Phytozoa, Plates. Berlin, 1828; text, 1831.
PI. I., fig. 11, Diurella podura (= Ichthydium).
*30. Hlava, S. Syst. Stell. v. Polyarthra fusiformis Spencer.
Zoo. Anz., 28, pp. 8-9, December 1904.
New genus Stylochaeta (sp. S. fusiformis Spencer).
31. Imhof, 0. Tiefseefauna — SUsswasserbecken. Zoo. Anz., 8,
p. 325, 1885.
Found C. maximus as an abyssal species in lakes.
32. Joblot. Nouvelles Observations, p. 79, PI. 10, fig. 22, 1718.
" Poisson a la tete faite en trefle " ( = /. podura).
33. Kojevnikof, G. Faune de la mer Baltique orientale.
• Congres intern. Zool. II., Moscow, pp. 132-57, 1892.
I have been unable to find this work.
34. Lamarck. Hist. nat. des Animaux sans vertebre, p. 447, 1850.
Furcocerca podura ( = Ichthydium).
*35. Lauterborn, R. Rot. -Fauna d. Rheins u. s. Altwasser.
Zool. Jahrb., 7, Syst., pp. 1^54-73, PI. 11, 1893.
New species — Dasydytes zelinkai, C. mawacanihus . The
description shows D. zelinkai as a not very distinct variety
of D. goniathrix Gosse. No figure is given. C. macra-
canthus appears to be C. entzii Dad.
36. Ibid. Die sapropelische Lebewelt. Zoo. Anz., 24, pp. 50-55,
1901.
Dasydytes zelinkai (see previous paper).
J. MURRAY ON GASTROTRICHA. 233
37. Lucks, R. Linaugebiet micr.-Wasserbewohner. Jahrb. West-
preuss. Lehrver.f. Naturk., pp. 20-23 (1905), 1906.
List of eight known species in West Prussia.
38. Ibid. Neues aus d. Mikrofauna Westpreussens. Ber. West-
preuss. Bot.-Zool. Ver., 31, pp. 141-2, 1909.
Three additional known species in West Prussia.
39. Ludwig, K. TJ. d. Ordnung Gastrotrichs. Zeit. far iviss.
Zool., 26, pp. 219-25, 1875.
A general work, dealing with systematic position, etc.
List of thirteen known species.
*40. Marcolongo, I. Primo contributo alio studio dei Gastro-
trichi del lago-stagno craterico di Astroni. Monitore Zool.
Ital. Firenze, 21, pp. 315-18, 1910.
He gives no figures, but describes a new family
Anacanthodermidae, a new genus linacanthoderraa, and
eight new species — Chaetonotus laroides, C. hirsutus, C.
minimus, C. nodifarca, C. decemsetosus, C. 2)aucisetosus,
Dasydytes imucisetosus, Anacanthoderma punctatum.
I have not seen this paper, but received these particulars
by favour of Mr. Harring, of Washington. (Vide No. 72.)
*41. Metchnikoff, E. Wenig-bekannte niedere Thierformen.
Zeit. fur wiss. Zool, 4, pp. 450-8, PI. 15, 1865. English
trans, in Journ. Jlicr. Sd. (N.S. 6), pp. 241-52, 1865.
New genera — Chaetura (sp. capr worms), Cephalidium
(= Dasydytes) (sp. longisetosum). New species — Ichthy-
dium oceUatum, C. hystrix, C schultzei.
*42. Muller, O. F. Verm. terr. etfluv., pp. 66 and 79, 1773.
New species — Cercaria podura (= Ichthydiam), Trichoda
acarus and T. anas (both now = C. larus).
*43. Ibid. Prod. Zool. Dan., 1776.
Trichoda lai'us ( = Chaetonotus).
44. Ibid. Anim. infus.fluv. et marina, 1786.
Trichoda larus (— Chaetonotus).
45. Nitzsch. Infusorienkunde, 1817.
Enchelys podura ( = Ichthydium).
46. Norrikov, A. Y. K. sistematikie Gastrotiicha (Russian).
Triid. Obs. Ahklim. Moskau, 6, 1907, pp. 309-47, PI. 10.
I have not seen this paper, but Mr. Harring, who kindly
furnished the reference, says it is largely a translation of
Zelinka's paper (71) and contains little that is new.
Journ. Q. M. C., Series II.— No. 73. 16
234 J. MURRAY ON GASTROTRICHA.
47. Parsons, F. A. In the Quekett Journal for 1896-7 there
occur some records of Gastrotricha found at the excursions
of the Club. I do not know who made the actual iden-
tifications, but the records are referred to in Mr. Parsons's
name by various authors.
48. Perrier, E. Traits de Zoologie, Fasc. 4, pp. 1534-9, figs.
1103-5, 1897.
A general account of six species, with some figures.
49. Perty, M. Kleinste Lebensfovmen dev Schweiz, p. 47, 1852.
A few remarks on the group and several known species.
50. Pritchard, A. History of Infusoria, 1861.
The earlier editions of Pritchard contain a few notes
after Ehrenberg. In 1861 there is a fair account of the
group.
*51. Schimkewitsch, W. M. Neue Species Ichthydium. Nachr.
K. Ges. Freunde d. Natuv., 50, 1886 (/. bogdanovii).
*52. Schmarda, L. K. Neue wivbellose Thieve, i. 2, 1861.
Describes two new species as Ichthydium — /. jamaicense
and /. tabulatum — which are technically Chaetonotus,
according to his own generic definition of Ichthydium.
53. Schrank, P. v. P. Beitvdge ficv Natuvgeschichte, 1776.
His Bvacliionus pilosus (Part III., PI. 4, fig. 32) is,
according to Dujardin (16, p. 570, footnote), Chaetonotus
lav us.
54. Ibid. Fauna Boica, hi., pp. 90-91, 1803.
Tvichoda lavus ( = Bvacliionus pilosus), T. anas.
55. Schultze, M. Ueber Chaetonotus mid Ichthydium Ehr.
Avcli. f. Anat. u. Phys., vi., pp. 241-54.
New genus Tuvbanella, which I believe is not a
Gastrotrich.
*56. Spencer. On a new Rotifer, Polyavthva fusifovmis.
This is a Gastrotrich, since made the type of a new
genus, Stylochaeta, by Hlava (30). J. Q. M. C, 1890, p. 59.
*57. Stokes, A. C. Observations on Chaetonotus. The Micro-
scope (American), vol. 7, two parts, January and February,
1887, pp. 1-9, PI. 1 ; pp. 33-43, PI. 2.
One of the most considerable works on the group, in
which a great many new species are described. They are
all regarded as Chaetonotus, the earlier generic distinctions
not being admitted.
J. MURRAY OX GASTROTRICHA. 235
New species — 0. sulcatus, C. concinnus, C. loricatus,
C. rhomboides, C. spinifer, C. acanthodes, C. octonarius,
C. spinulosus, C. longispinosus, C. enormis, C. acantho-
jjhorus.
Apparently good figures are given of all of these species,
and of species of other authors, but Stokes claims indul-
gence for inaccuracies in all his figures.
58. Ibid. Observations sur les Chaetonotus. Journ. de Microg.,
II, 3 parts, February, April, December, 1887, pp. 77-84,
150-3, 560-6, PI. 1 and 2.
Simply a translation of the American paper, with the
same plates.
*59. Ibid. Observation on a new Dasydytes and a new
Chaetonotus. The Microscope, vol. 7, pp. 261-5, 1 PI., 1887.
New species — D. saltitans, C. formosus.
60. Ibid. Observations sur les Chaetonotus et les Dasydytes.
Journ. de Microg., 12, 2 parts, January, 1888.
A translation of the preceding paper.
*61. Tatem, T. G. New Species of Microscopic Animals. Quart.
Journ. of Micr. Sci., N.S. 7, pp. 251-2, 1867.
New species — Chaetonotus longicaudatus.
*62. Thompson, P. G. A new species of Dasydytes. Science
Gossip, No. 319, 1891.
New species — D. bisetosus.
*63. Yoigt, M. Bisher unbekannte Siisswasserorganismen.
Zool. Anz., xxiv., No. 640, pp. 191-4, 1901.
New species — Chaetonotus serraticaadus, C. nodicaudus.
*64. Ibid. Unbesehriebene ' Organ. Plon. Gewassern. Zool.
Anz., xxv., No. 660, pp. 35-9, 1901.
New species — Ichthydium forcipatum, Chaetonotus- chuni,
Dasydytes stylifer.
*65. Ibid. Rot. u. Gast. d. Umgebung v. Plon. Zool. Anz., xxv.,
No. 692, pp. 673-81, 1902.
He names nine species as new, but gives no descriptions
or figures except of one. Eight of them had been de-
scribed in earlier papers. The nine names are Ichthydium
forcijxitum, Aspidonotus paradoxus (n. gen., n. sp.), Chae-
tonotus linguaeformis, C. nodicaudus, C. serraticaudus, C.
uncinus, C. succinctus, C. chuni, Dasydytes stylifer. He
describes Aspidonotus and (p. 681) figures one scale.
236 J. MURRAY ON GASTROTRICHA.
*66. Ibid. Drei neue Ohaetonotus-Arten a. Plon. Gew'assern.
Zool. Anz., xxv., No. 662, pp. 116-18, January, 1902.
New species — C. linguaeformis, C. succinctus, C. uncinus.
*67. Ibid. Erne neue Gastrotrichenspecies (Chaetonotus arquatus)
aus dem Schlossparkteiche zu Plon. Forschber. Biol. Stat.
Plon., x., pp. 1-4, 1903.
68. Ibid. Rotatorien u. Gastrotrichen d. TJmgebung von Plon.
Ploner Forsch.-ber., xi., 180 pp., 1904.
He records twenty-three species and describes nine as
new, but these have been described in earlier papers. He
renames the genus he had called Aspidonotus, making it
Aspidiophorus, as he found that the former name was
preoccupied.
*69. Ibid. Nachtrag zur Gastrotrichen-Fauna Plons. Zool.
Anz., xxxiv., No. 24/25, pp. 717-22, 1909.
New species — Chaetonotus ploenensis, C. simrothi, Dasy-
dytes dubius, D. festinans, D. ornatus.
70. Wagner, F. Der Organismus der Gastrotrichen. Biol.
Centralb., 3, No. 7/8, 1893.
•71. Zelinka, C. Die Gastrotrichen. Zeit. f. iviss. Zool., 49,
pp. 299-476, PI. 11-15, 1889.
An important paper, the most careful and scientific
that has appeared on the subject. He gives a good and
full account of the anatomy, a good bibliography, and a
good resume of all the systematic work on the group,
quoting most of the authors' original descriptions. Some
previously described species escaped his notice, as Ichthy-
dium entzii Dad. Two new genera and four new species
are described. The genus Gossea is framed to contain
Gosse's Dasydytes antenniger, Lepidoderma for Dujardin's
Chaetonotus squammatus, with C. rhomboides Stokes,
Ichthydium ocellatum Metch., and C. concinnum Stokes.
Lepidoderma is an unfortunate genus, as the type species
(C. squammatus Duj.) is spiny and a true Chaetonotus. C.
rhomboides Stokes is usually spiny, and /. ocellatum Metch.
is not stated or figured by its discoverer to have scales.
The new species are— Chaetonotus similis, C. brevi-
spinosus, C. Qiiacrochaetus, C. persetosus.
72. Marcolongo, Ines. I Gastrotrichi del lago-stagno craterico
di Astroni. Atti Ace. Sci. Fio. e Nat. Napoli, vol. 14.
J. MURRAY ON GASTROTRICHA. 237
Explanation of Plate 19.
Scale and hair of :
Fig. 1. G. macrochaetus Zel. (After Zelinka.)
55
?5
55
55
?5
55
55
55
55
55
55
55
55
55
55
55
?>
fl
55
55
)5
55
9
6'. hystrix Metsch.
3. C. si?nilis Zel. (After Zelinka.)
4. C. maximus Ehr. (After Zelinka.)
5. G. persetosus Zel. (After Zelinka.)
6. G. pusillus Dad. (After Daday.)
7. C heterochaetus Dad. (After Daday.)
8. C. schidtzei Metch. (After Zelinka.)
9. G. larus Miill. (After Ludwig.)
10. C. erinaceus Dad. (After Daday.)
11 a. G. succinctus Voigt, one of the long bristles. (After
Voigt.)
116. C. succinctus Yoigt, scale from posterior part. (After
Voigt.)
12. G. hystrix Metsch. (After Zelinka.)
13. C. nodicaudus Voigt. (After Voigt.)
14. Aspidiophor us paradoxus Voigt. (After Voigt.)
15. Lepidoderma ehngata Dad. (After Daday.)
16. C. brevispinosus Zel. (After Zelinka.)
17. C. arquatus Voigt. (After Voigt.)
18. G. simrothi Voigt. (After Voigt.)
19. G. zelinkai Grim. (After Griinspan.)
20. C. uncinus Voigt. (After Voigt.)
21. G. chuni Voigt. (After Voigt.)
22. C. linyuaeformis Voigt. (After Voigt.)
23. Ichthydium sp. (?).
24. Lepidoderma loricata Stokes. (After Stokes.)
25a. Dasydytes goniathrix Gosse. Drawn from nature.
256. D. goniathrix Gosse. A single seta.
26. C. entzii Dad. (?). Differs from Daday's in having the
furca without hairs.
27. Dasydytes bisetosus Thomp. Drawn from nature.
28a. Gossea antennigera Gosse. Drawn from nature.
286. G. antennigera Gosse. Scale and hair.
?, 29. Lepidoderma, very small species. Drawn from life.
238 J. MURRAY ON GASTROTRICHA.
Fig. 30. Chaetonotus sp. (?). Scales as in C. larus (fig. 9), but
rows more numerous.
31«. Chaetonotus sp. (?). With very distinct rhomboid scales.
316. Chaetonotus sp. (?). Three of the scales.
32. Setopus primus Griin. (After Griinspan.)
33. Chaetura piscator sp. n.
34. Chaetonotus sp. (?). All hairs long, widely spreading.
35. Chaetonotus or Lepidoderma. Like the animal figured
by Zelinka as L. ocellatam Met., but I saw no
eyelike bodies. Metchnikoff did not describe his
animal as scaly.
,, 36. Scales of C. tenuis Griin. (After Griinspan.)
Journ. Qvekett Microscopical Club, Ser. 2, Vol. XII., No. 73, November 1913.
Ser. 2, Vol. XII., PI. 19.
J. Murray, del. adnat.
Gastrotricha.
239
NOTES
ON A NEW METHOD OF MEASURING THE
MAGNIFYING POWER OF A MICROSCOPE.
By Edward M. Nelson, F.R.M.S.
{Read June 2Wi, 1913.)
Many microscopists, at one time or another, will have experienced
some trouble about the determination of the combined magni-
fying powers of their objectives and eyepieces. Some never
measure them at all, and rely upon the manufacturer's catalogues
for the results. This is not very satisfactory, for neither
objectives nor eyepieces turn out to be at precisely their nominal
foci ; and if both these should happen to be either in excess or
deficit the actual magnifying power will differ considerably from
that given in the catalogue. Therefore it will be better for every
one to measure the magnifying powers of the lenses of their
microscope.
There are two well-known methods of doing this. The first,
and perhaps the simplest, is to employ a photomicrographic
camera to measure the magnified image of the stage micro-
meter when projected on to the ground glass at a distance of ten
inches. The second is to project the magnified image of the
stage micrometer, by means of some sort of a camera lucida, on to
a scale, distant ten inches as before.
All this appears delightfully simple, but w^hen examined more
carefully it is not really so. First, the photomicrographic-camera
method requires a dark room, or the measurement must be made
at night, and of course it is sure to happen that when the
camera is most wanted it is not available. This is just what has
occurred to me. My photomicrographic camera and stand, which
240 E. M. NELSON ON A NEW METHOD OF MEASURING THE
are large and heavy, are packed away ; it would take some
hours to unpack them, clear out a room for their reception,
bring them in and set them up, so I have to be content with
some other means of measuring magnifying powers.
The second method, viz. that of employing a camera lucida,
also appears to be very simple, and so it is when a Powell No. 1
stand is used, which has its optic axis ten inches from the table,
when inclined horizontally ; a Beale's neutral tint fitting on the
" capped" eyepieces answers perfectly — some attention, however,
is necessary to regulate the illumination, both in the tube and on
the rule, otherwise the coincidences of the lines cannot be
observed. But suppose a continental eyepiece is used, what
then ? The Beale camera will not fit, and all the simplicity of
one's arrangements and apparatus fails. If the microscope is
not a Powell's No. 1, then it must be placed upon a box, and the
distance of the rule adjusted by means of other boxes, books,
etc. With a Continental microscope matters are no better. One
has the simplicity of the Abbe camera, with its cleverly planned
device for regulating the illumination of the stage micrometer
and of the rule, but suppose the eyepiece is of the positive com-
pensating type, what is to be done ? The camera will not fit
and cannot be used. There are other cameras, both of the right-
angled and of the oblique type ; some eyepieces they fit and
others they do not. These difficulties are not imaginary, for
I have experienced all of them at one time or another. The
apparatus I now use is the old-fashioned Wollaston's camera,
mounted on a table screw clamp. This can be used with every
kind of eyepiece ; it is, however, troublesome to work with, and
it requires some practice to obtain a coincidence of the scales —
how anybody can execute a drawing with such an apparatus is,
to me, quite incomprehensible !
I have devised an entirely new method by which all these
worrying little troubles may be avoided. First, it is necessary
to determine the " constant " of the eyepiece with a given tube
length. This is easily done, and when done it should be recorded,
or better still engraved on the eyepiece tube. To find the
" constant " of an eyepiece with a given tube length, first
determine the combined magnifying power of that eyepiece on
the given tube length with any objective, say one of medium
power, sudh as a |-in. or J-in. or |%-in. focus. Secondly, measure
MAGNIFYING POWER OF A MICROSCOPE. 241
the exact diameter of the field by means of the stage micro-
meter. The product of these two quantities is the constant of
that eyepiece with the given tube length.
Example : objective §-in., eyepiece compensating x 8, tube
length 170 mm., measured magnifying power 280 diams. :
measured field 0-023 in. Product is 6'44, which is the constant
of that eyepiece for 170-mm. tube.
The power of any other objective with this eyepiece and tube
length can be determined by merely measuring the diameter of its
field by the stage micrometer ; for the magnifying power will ob-
viously be the eyepiece constant divided by the diameter of the field.
Thus, the problem of measuring the combined magnifying
power is brought down to the bed-rock of simplicity. No camera,
no regulation of illumination, no ten inches to measure ; in brief,
nothing to do but to count the number of divisions of the stage
micrometer in a diameter of the field and then divide this into
the eyepiece constant.
Example 1. With the same x8 compensating eyepiece and
170-mm. tube a |--in. objective gave a diameter of field of
6-44
0*0165 in. The magnifying power therefore is rw = 390.
Example 2. With the same x 8 compensating eyepiece and
1 70-mm. tube a 1 J-in. objective gave a diameter of field of 0*185 in.
„ 6-44
The magnifying power therefore is .... = 35.
The determination of the constant is scarcely any more trouble
than the measurement of the magnifying power of one objective,
and when once found need not be determined again ; it would
ndeed be most helpful if manufacturers would measure these
constants and engrave them upon the tubes of their eyepieces.
Obviously the diameter of the field can be measured while the
microscope work in hand is being carried on, for it disturbs neither
the microscope nor its adjustments.
This method has been tested with thirty- three object glasses,
ranging from a 3-in. to a yTrth of 1'4 IS". A., by fourteen different
makers, and with various eyepieces, on three different microscopes
with different tube lengths, and it has been found correct.
My best thanks are due to Mr. Grundy for his kind assistance and
notes. Further experience has shown that in determining the
" constant " it is better to measure the magnifying power by
242 E. M. NELSON ON A NEW METHOD OF MEASURING THE
direct projection on to a scale, without the intervention of any
camera lucida or drawing instrument ; the position of the
Ramsden's disc, from which the 10-in. projection distance is
measured, is easily found by means of a piece of ground glass.
An excellent scale for the measurement of low powers is a
Lufkin 3-in., No. 2111, price Is.
[Practical members ma}7, by this time, be ready to ask, " What
is the practical use of this system ? ' As a general answer it
might be said that it shows how the materials for an important
microscopical measuring tool can be easily determined.
But another practical reason for my taking interest in our
veteran member's paper is the hope that it will stimulate some
of us to take an increased interest in microscopical measurements.
I hardly need to impress on members the value of actually
measuring objects, beyond offering a reminder, that measurements
are the fundamental basis of microscopical science, and of every
branch of science. Some would, perhaps, claim to put mathe-
matics in this honourable position, but mathematics would be in
a most sorry plight without measurements in various forms.
Mr. Nelson, in a letter, says : " The combined magnifying
power is wanted for drawings. Beale's method of exhibiting a
drawing of the stage micrometer with the picture is quite the
best, but it is adopted by only a few authors." And he mentions
an instance of great trouble being caused by some drawings in
books on microscopical subjects having the magnifications wrongly
stated in the legend.
It will have been noticed that Mr. Nelson has, hitherto, con-
fined the use of the "eyepiece constant," for one eyepiece, to one
definite tube length for one constant ; but used it for getting
the total magnification with varying powers of objectives.
Tests have, however, shown that the total magnification can be
determined, by his method, for different tube lengths just in the
same way as for different powers of objectives. Mr. Nelson
himself says that " increase of tube length increases the power
and, of course, diminishes the field, and is just the same as
putting a higher-power objective on the nosepiece ; the constant
of the eyepiece remains the same." In support of this statement,
I give belowr a few of the results of experiments made by Mr.
Nelson not many days ago.
MAGNIFYING POWER OF A MICROSCOPE.
243
Tests with Powell & Lealand's Low-angled ^in. Objective.
Eyepiece.
Tube length.
Diameter of field.
Magnifying power.
Eyepiece constant.
No. 1
12 in.
♦5 .,
0-036
0-0675
103
56
3-708
3-7N
No. 2
12 in.
6 „
0-031
0-0615
135
7(>
4-185
4-305
No. 4
12 in.
6 „
0-0267
0-052
267
135
7-129
7-02
Other Tests with ^-in. Objective.
Eyepiece constants.
Eyepiece.
Tube length, 8*75 in.
Tube length, 6-7 in.
A(E)
Z 12 C
W 1
2
K3
613
5-2
3-69
413
5-64
6-04
51
3-54
4-10
5-6
Tube length, 14*6 in.
Tube length, 5 -3 in.
K3
5-62
5-64
Magnifications . . 250
94
Notice how nearly alike the eyepiece constant is for each pair
of tests when different tube lengths are used, but the same eye-
piece and objective. The last pair are practically the same,
although the tube lengths vary to an extraordinary extent.
Mr. Nelson says that "they are all done with extreme accuracy
by projection. In every case the Ramsden's disc was found and
the screen placed ten inches from it." The magnifications were
250 and 94 diameters.
There is another easy way in which the information given by
the " eyepiece constant " may be used for determining the total
magnification for any tube length. Suppose, for example, the
eyepiece constant has been obtained with a given objective, eye-
piece, and tube length, a record being made ; then it is only
necessary to work a very simple proportion sum to determine — at
any time — the total approximate magnification with any tube
244 E. M. NELSON ON MAGNIFYING POWER OF A MICROSCOPE
length. All other conditions being the same, the total mag-
nification will be proportional to the tube lengths used.
Take the extraordinary difference of tube length shown by the
figures given below :
Tube length. Magnification.
14-6 in. 250
5-3 in. 94
Then
Magnifica-
Magnification with long tube x short tube length 250 x 5-3 tion for
short tube
length.
Magnifica-
tion for
Snort tube length. 5#3 ' long tube
length.
It is also worth mentioning that the diameter of the field may
be measured in millimetres, instead of inches, if millimetres are
used when determining the value of the eyepiece constant. And
members will probably find this a great convenience.
J. Grundy.]
Long tube length
14-6
And
Magnification with short tube x long tube length
94 x 14-6
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII. , No. 73. November 1913.
245
PROCEEDINGS
OF THE
QUEKETT MICROSCOPICAL CLUB.
At the meeting of the Club held on March 25th, 1913, the
President, Prof. A. Dendy, D.Sc, F.R.S., in the chair, the
minutes of the meeting held on February 25th were read and
confirmed.
Messrs. J. T. Cook, David Henry Shuckard and W. E.
Ford-Fone were balloted for and duly elected members of the
Club.
The Hon. Secretary announced that Mr. G. T. Harris, of
Sidmouth, a former member of the Club, had made a very
handsome donation in the form of a type collection of Hydrozoa,
numbering 72 preparations. These had been collected on the
south-west and west coasts of England, and should prove
very useful to any member making a systematic study of the
group, especially as the slides are accompanied by a resume as
a help in diagnosing the more difficult species. Mr. Harris
also sent a paper which will be read at the next meeting, on
"The Collection and Preservation of the Hydrozoa."
A vote of thanks to Mr. Harris for his valuable donation
was proposed by the President, and carried by acclamation.
Mr. A. A. C. Eliot Merlin, F.R M.S., sent for exhibition five
photomicrographs, taken at x 320, of diatoms from a slide
prepared by the late C. Haughton Gill (see Journal R.M.S.,
1890, p. 435). They were of Epithemia turgida, Stauroneis
phoenice7ite?'07i, Pinnularia major, under surface showing per-
forations on ribbing partly filled with the mercurous sulphide,
and two others.
A paper by Messrs. Heron-Allen and Earland, "On some
Foraminifera from the Southern Area of the North Sea, dredged
by the Fisheries cruiser ' Huxley ,'" was read by Mr. Earland.
Mr. Earland said that after the reading of the paper by Mr.
Heron-Allen and himself, " On the Occurrence of Saccammina
246 PROCEEDINGS OF THE
sphaerica and Psammosphaeria fitsca," before the " Challenger "
society in October of last year, Mr. J. 0. Borley, of the Fisheries
Department of the Board of Agriculture, suggested that it would
be interesting if they continued their investigations in the
southern area of the North Sea with a view to determining the
distribution of the two species in that area. This, after some
hesitation, they agreed to do ; but with little expectation that
any observations of interest would result, as Mr. Borley had
already confirmed, from his personal experience, the generally
held opinion that Foraminifera of all kinds were of extremely
rare occurrence in these waters. The shallowness of the sea,
and consequent disturbance due to wave and tidal action, were
considered to be factors limiting the possibilities of Khizopodal
distribution. Material was examined from six stations repre-
senting two widely separated areas of the North Sea, three
stations being far to the north-east of the Dogger Bank near the
Great Fisher Bank, while the other three stations were in the
belt of deep water which lies to the west of the Dogger, close in
to the Northumberland coast. The depths ranged between 31
and 45 fathoms.
A number of photomicrographs were projected upon the screen,
and briefly described by Mr. Earland. Nubecidaria lucifuga
(Def ranee), a southern form, has an extended range as far as
the English Channel. It is common at Bognor and Selsey, and
a few specimens had been found near the Orkneys and in Moray
Firth. Miliolina seminulum (Linne) occurs at every station in
both areas. It is the dominant miliolid of the North Sea, and
is of world-wide distribution. Of the two species especially
searched for Psammosphaera fusca (Schulze) was found to occur
at all stations except one in the inshore area. Saccammina
sphaerica (Sars) does not occur in any of the outer, or Great
Fisher Bank, collections, but does occur at two inshore stations.
The specimens found were extremely small. The dominant
arenaceous form was Eeophax scorpiurus (Montfort). The
dominant Textularian was Verneuilina polystropha. It occurred
in great numbers and variety at every station. The genus
Lagena is abundantly represented in the inshore station dredg-
ings, twenty-eight species being recorded, while at the outer
stations only eight species were found. Truncatidina lobatula
(W. and J.), Nonionina depressula (W. and J.), and Polystomella
QUEKETT MICROSCOPICAL CLUB. 247
striato-punctata (F. and M.) occur abundantly everywhere, and
form the bulk of all the cleaned material.
The President, in proposing a vote of thanks for the paper,
said he much admired the photographs shown, which were the
best of the kind he had seen. He would like to ask Mr. Ear-
land, with regard to the criteria of specific characters, How
could one tell one species from another, seeing that there is so
much variation within the same species ?
The vote of thanks was carried unanimously.
In replying, Mr. Earland said he had to thank Mr. A. E.
Smith for making the negatives, and Mr. Lovegrove for the
lantern slides. Regarding specific differences, probably Prof.
Dendy would have no difficulty in identifying sponges which he
(Mr. Earland) would not be able to tell one from another.
There are constant points always present which make it more
or less easy to diagnose within certain limits. As regards specific
features in Foraminifera, there are none such as we find between,
say, a cat and a dog. Probably generic differences in Fora-
minifera are about equal to specific differences in higher forms.
Mr. D. Bryce gave a resume of a paper he had contributed
on " Five New Species of Bdelloid Rotifers." Four of the new
species belong to that important section of the Philodiniclae in
which the food is formed into pellets after passing through the
mastax, and are assigned to the genus Habrotrocha. The new
species are IT. munda, H. torquata, U. spicida, and H. ligula.
The fifth species, Callidina Bilfingeri, belongs to the more
numerous section of the same family in which the food is not
at any time agglutinated into pellets, and being oviparous, and
possessed of three toes, is a member of the genus Callidina, as
now restricted.
The President said they were all much indebted to Mr. Bryce
for bringing these interesting details before them.
A vote of thanks to Mr. Brvce for his communication was
carried unanimously.
At the meeting of the Club held on April 22nd, 1913, the
Vice-President, E. J. Spitta, L.R.C.P., M.R.C.S., in the chair,
the minutes of the meeting held on March 25th were read and
confirmed.
248 PROCEEDINGS OF THE
Messrs. F. J. Cheshire, Henry Edwards, and H. D. Rawson
were balloted for and duly elected members of the Club.
The List of Donations to the Club was read and the thanks of
the members voted to the donors.
Mr. C. D. Soar, F.R.M.S., read a note describing two new
species of water-mites. These were Arrhenurus Scourfeldi sp.
now and Acercus longitarsus sp. nov.. The first was taken by
Mr. Scourfield in Cornwall, in fresh water, in the autumn of
1912. It belongs to the sub-genus Megalurus, female unknown.
The new species of Acercus is named from the unusually long
tarsi found in the fourth pair of legs. Locality, South .Devon-
shire, female unknown. Mr. Soar also said that Mr. Williamson,
F.R.S.E., in working out the material on the genus Sperchon
had found two species new to Britain, and two that have only
been recorded for Ireland. These were Sperchon clupeifer Pier,
sub-genus Hispidosperchon, from Oban and Norfolk Broads.
Sperchon tenuabllis Koen, sub-genus Hispidosperchon, from
Oban. Recorded by Halbertin Clare Island Survey for Ireland.
Sperchon papillosus, Sig. Thor, sub-genus Squamosus, Oban,
recorded by Halbert for Ireland ; and Sperchon Thienemanni,
Koen, sub-genus Rugosa, from Derbyshire. Drawings of the
two new species were exhibited.
The Chairman said they were all deeply indebted to Mr. Soar
for bringing these new species of Hydrachnidae before them, and
they would be able to appreciate the value of the paper more
when in print. The drawings in illustration of the species
described were very tine indeed.
The thanks of the meeting were unanimously voted to Mr. Soar
for his paper.
In the absence of the author, the Hon. Treasurer, Mr. F. J.
Perks, read a paper on " The Collection and Preservation of the
Hydroida," by Mr. G. T. Harris, of Sidmouth, a former member
of the Club. The author said that the Hydroida are too well
known as affording both beautiful and interesting objects to need
any eulogy at his hands. Bearing in mind that this paper is
written more for the help of the novice than as a communication
offering original matter, the writer wished to safeguard himself
from any charge of carelessness by warning the uninitiated that
collecting, say, rotifers and collecting hydroids are two totally and
very dissimilar things.
QUEKETT MICROSCOPICAL CLUB. 249
A hearty vote of thanks was given to Mr. Harris for his
interesting paper, which was well illustrated by about twenty
preparations from those which he had presented to the Club at
the March meeting. The preparations were arranged, mostly
with dark-ground illumination, under microscopes kindly lent by
Messrs. H. F. Angus & Co.
The Chairman, in moving a vote of thanks to Messrs. Angus,
which was carried bv acclamation, said that in London members
took for granted that there was never any difficulty in getting
their optician friends to lend the Club any reasonable number of
microscopes ; but, as he had found by recent experience, outside
of London such a thing was practically an impossibility ; even in a
large town the number of microscopes available was very small.
By being reminded of this he hoped they would more fully appre-
ciate their good fortune.
At the meeting of the Club held on May 27th, 1913, the
President, Prof. A. Dendy, D.Sc, F.R.S., in the chair, the
minutes of the meeting held on May 22nd were read and con-
firmed.
Messrs. Stanley Hall and Reginald Hook were balloted for and
duly elected members of the Club.
The list of donations to the Club was read and the thanks of
the members were voted to the donors.
The President said that for many years past a number of
pamphlets, etc., had been received by the Club, which, not being
considered of sufficient value to bind, had bden allowed to
accumulate and were stored in a room downstairs. These had
long been a kind of white elephant to the Committee, who had at
length decided to deal with them, and had appointed a sub-com-
mittee for this purpose. These gentlemen had gone through
them and had come to the conclusion that a large mass of this
material must be disposed of, and the question arose as to how
this was to be done, and it had been resolved to offer the bulk to
some dealer in second-hand books, but first of all to offer them to
the members of the Club. For this purpose, lists would be pre-
pared and laid upon the table at the next Gossip meeting and
again at the next Ordinary meeting, for members to inspect and
to make offers for any which they might care to possess. The
Journ. Q. M. C„ Series II.— No. 73. 17
260 PROCEEDINGS OF THE
Librarian was empowered to receive such offers for them and to
accept those which he deemed satisfactory. It was not possible
to bring them up for inspection, as there was about a ton and
a half of them.
A visitor, Mr. J. Watson, exhibited multiple images formed by
the cornea of the eye of a hive bee mounted dry.
Mr. J. Watson said the slide was that of the eye of a honey
bee prepared so as to show the portrait of the bee-keeper in every
facet just as the bee would see it. He had been told it could be
done with the eye of a beetle, but that the hairs on the eye of the
bee made it a difficult matter to accomplish; but by mounting the
object in the way he described, so that the hairs were free from
pressure on the under side of the slide, he had succeeded in
obtaining the desired result, and he had obtained a good photo-
graph of it with half an hour's exposure.
The President said that at a Society such as theirs it wras
needless to explain that this was not the view which the bee got,
as no doubt in some way it saw a single image, but he just men-
tioned this to prevent any mistake, as he thought he heard it
stated that this was how the bee saw the bee-master. Multiple
images such as were shown could be got in a variety of ways, and
he remembered that exactly the same thing was done at one of
the Royal Society's soirees with the epidermic cells of a plant.
They were, however, much obliged to Mr. Watson for bringing
and explaining his exhibit.
Mr. E. Inwards had found that a small knob fitted near the
hinge -joint of the stop-carrier of substage condensers was more
convenient in working than having to feel on the right for the
usual long projecting end, which is very often in close proximity
to the iris-handle.
Mr. T. A. O'Donohoe read a paper illustrated by a number of
lantern photographs, at various degrees of magnification, of the
" Minute Structure of Coscinodiscus asteromjrfialus and of the two
species of Plenrosigma, P. angulatium and P. balticum. Mr.
O'Donohoe then showed an interesting series of photographs, at
various magnifications, of P. balticum, some showing fine, hair-
like, bent fibrils breaking away from the valve. Others showed
the outer membrane breaking up into fibrils, and sometimes
isolated dots.
Mr. W. E. Brown said that the fibrils shown by Mr. O'Donohoe
QUEKETT MICROSCOPICAL CLUB. 251
had been known to him for a long time, but lie had never
regarded them as structure, but rather as salt which had
crystallised out after mounting. All these fibrils consisted of
rows of dots connected by bars, and there always seemed to him
to be some difference between these and the general structure.
Mr. E. Pitt exhibited and described the Cambridge, Minot and
Spencer microtomes, and, after the adjournment of the meeting,
gave a demonstration of ribbon section-cutting.
A vote of thanks was accorded Mr. Pitt for his exhibition.
At the meeting of the Club held on June 24th, 1913, the
President, Prof. A. Dendy, D.Sc, F.R.S., in the chair, the
minutes of the meeting held on May 27th were read and con-
firmed.
Messrs. Frank Deed, C. Tierney, D. L. Newmarch, E. L.
Fen wick, and H. H. Dean were balloted for and duly elected
members of the Club.
The list of donations to the Club was read, and the thanks
of the members voted to the donors.
The Hon. Secretary read a note from Mr. E. M. Nelson
describing Koristka's new loup. The writer said that in 1885
he brought to the notice of the Club the then new Zeiss-Steinheil
loups, which had just arrived from Jena. These lenses have been
very popular, and have since been copied by every maker, both
here and on the Continent.
There is now a new form of loup with which the Club should be
acquainted; it is the achromatic doublet of Koristka. The following
are the measured particulars (not taken from a catalogue) :
Doublet, power 10, field 1| cm., working distance 2 cm.
Top lens alone, ,, 5|, ,, 2 „ „ ,, 4 „
Bottom lens alone, ,, 3|, „ 4 ,, „ ,, 5 „
The defining powrer of this loup is excellent, and prolonged
work with it seems easier than with a Steinheil ; somehow or
other work with a Steinheil is tiring to the eye. The price of
this fine lens, in a wooden box, is only 12s., but although the
price is so low, the quality of workmanship is particularly high.
Among cheap loups we so often find that the lenses are im-
perfectly polished, the threads of the screws badly cut, so that
they do not engage readily, and the quality of materials used
252 PROCEEDINGS OF THE
inferior. But this new loup exhibits none of these defects, and
Koristka is to be congratulated on having brought out at a low-
figure a loup which compares favourably in the quality of its
finish with the most expensive grades of work in this line. This
high standard of workmanship extends also to Koristka's
objectives, eye-pieces and other apparatus.
Mr. A. A. C. Eliot Merlin, F.R.M.S., sent a note on " Secondary
Hairs on Foot of a Ceylon Spider." The main hairs on the foot
of a very large species of Ceylon spider, the name of which is
unknown, have proved to be densely covered with small short
spines or hairs so transparent as to be observable with difficulty
even by means of an oil-immersion objective. The specimen
examined was obtained and mounted in balsam by the late
Staniforth Green, who was for many years resident at Colombo.
When the main hairs are viewed with a dry lens, of moderately
large aperture they plainly exhibit a regular clotted structure,
this being composed of the ring root sockets of the secondary
spines, which are themselves so transparent in the balsam mount
as to require great aperture to define properly. It is suggested,
however, that hairs from this, or similar, large species of spider
might be mounted in glycerine jelly and might then exhibit the
spines more easily. The preparation in which the spines have
been noted happens to be, like most entomological mounts
intended for examination under low or medium powers, provided
with a cover-glass of considerable thickness, while the foot itself
is large and by no means flat. Under these conditions an
ordinary oil-immersion objective could not be employed, but
fortunately a Powell one-twelfth achromatic, of measured N.A.
1*27, obtained some fifteen years ago, possesses quite abnormal
working distance compared with recent productions of similar, or
slightly greater, aperture, and is to oil-immersion lenses what
the new one-sixth moderate aperture objectives of great working
distance are to dry systems. The lens in question has on several
occasions proved invaluable for the examination of minute
structure in ordinarily mounted entomological specimens. A
photomicrograph at x 60 accompanied the paper for identification
purpose, and was exhibited.
Mr. Nelson sent for exhibition a section of Green Trap, basic
igneous rock, a crystalline aggregation of serpentine. This, he
wrote, might easily be mistaken for a piece of fossil nummulite, or
QUEKETT MICROSCOPICAL CLUB. 253
wood. Xt is probable that the fossil known as Eozoon cauadense,
from the Laurentian serpentine, is of a similar nature.
Mr. H. Sidebottom contributed a valuable paper on "The
Lagenae of the South- West Pacific." Mr. A. Earland, F.R.M.S.,
in introducing this paper, said it was a very lengthy and valuable
one, and the Club would be proud to include it in the Journal.
It is Part 2 of a paper published in the April 1912 issue of
the Journal. By the kindness of Mr. H. F. Angus, who arranged
an exhibition frame for the drawings, he was able to exhibit
some of Mr. Sidebottom s beautiful drawings. The majority of
the stations from which the specimens dealt with were derived
(if not all) lie within the region of the South Pacific known to
oceanographers as the " Aldrich Deep." This area lies to the
east of New Zealand, between 15° and 47°, and covers about
613,000 square miles. Three soundings exceeding 5,000
fathoms have been recorded in this area by Commander Balfour
in H.M.S. "Penguin" in 1895. The deepest sounding yet
made, however, is one in the "Challenger" Deep, near Guam,
in the Ladrone Islands. This is 5,269 fathoms, nearly six miles.
The Aldrich Deep has the second deepest record, 5,155 fathoms.
None of the material discussed in this paper comes from the
deepest parts of the area. The depths given by Mr. Sidebottom
range between 328 fathoms and 4,278 fathoms, but the majority
are under 2,000 fathoms. No details are given of the nature
of the material from which the specimens were derived, and
possibly the information was not in the author's possession, as
the majority, at any rate, of the specimens had been picked out
by Mr. Thornhill prior to his death, when the type slides passed
into the hands of Mr. Sidebottom for classification and description.
It may, however, be fairly surmised that, owing to the distance
of the area from any land, none of the samples would be terri-
genous deposits, but would be true oceanic deposits. Globigerina
and Pteropod oozes in the lesser depths, passing into pure
Globigerina ooze, and, beyond the 2,000-fathom line, into Red
Clay. The presence of a varied and rich fauna of Lagenaa in
the deep water of the South Pacific has been recorded by the
" Challenger" Some of the stations of that ship lie within the
same area as the " Penguin " material worked by Mr. Sidebottom,
but the " Challenger " material was either very poor in specimens
compared with the "Penguin" or it was very incompletely
254 PROCEEDINGS OF THE
worked out. The genus Lagena, while of world-wide distribution
and occurring at all depths, presents some rather curious
anomalies as regards its occurrence in any abundance. It
would probably be almost impossible to make a dredging or a
shore gathering in any part of the world without finding the
genus represented in the material. But, Mr. Earland said,
from practical experience, both of deep and shallow water
dredging and of shore collecting, he knew that in one sample
the genus may be extremely rare, while in another of similar
material taken a few miles away, under similar conditions of
depth, the genus may be abundant and varied. The reason for
such a difference is obscure, but is possibly based on the pro-
portion of mud in the deposit. Legena as a genus is a lover of
still and muddy bottoms. Globigerina oozes are, as a general
rule, singularly poor in Lagenae : hence the greater wonder at
the richness of the fauna in these " Penguin " oozes. Mr.
Sidebottorn states that the late Mr. Thornhill had picked out
over 12,000 specimens, and had commenced to arrange them on
a scheme which he had devised but did not live to carry out.
Personally, Mr. Earland said, he regretted that Mr. Sidebottom
had not found time or opportunity to use the unique material
which came into his possession at Mr. Thornhill's death, as a
centre around which to build up a complete monograph of this
beautiful genus. Perhaps he may yet find himself able to deal
with this task. But, in any case, it is a matter for congratula-
tion that Mr. Thornhill's work did not perish and disappear
unrecognised on his death, as so often happens when a worker
dies, but that his material has fallen into the hands of Mr.
Sidebottom, whose beautiful drawings will make it accessible to
all interested in the group.
One of the most noticeable features of this group is the very
large proportion of decorated forms. Many of the recognised
species are very hard to identify on account of the almost in-
finite variety and variation of the minute spines and markings
which characterise them. The object of such markings seems
to be quite beyond speculation. They are quite invisible to the
naked eye, and, unlike the markings of diatoms, do not appear
to have any physiological significance. Mr. Earland thought
the Club was to be congratulated on obtaining two such notable
papers for publication in its Journal,
QUEKETT MICROSCOPICAL CLUB. 255
The President said that he was afraid he was not able to
throw any light on the significance of the markings and char-
acters of the kind Mr. Earland had mentioned. He thought
they were quite inexplicable at present. It must be admitted
that a great number of specific characters are not due to adapta-
tions, and one may go further and ask how far the origin of
species is affected by natural selection. What proportion of
specific characters are adaptations at all ? How often can one
say that any character is really adaptive ? He would like the
opinion of some of the Club workers. Would Mr. Rousselet,
for instance, say that all the specific characters of rotifers were
adaptations ? He would not say an organism wras not adapted
to its environment, but he would say that many organisms
exhibit a whole host of characters not due to environment.
They could not explain everything as due to natural selection.
Darwin laid great stress on " The Origin of Species by Means
of Natural Selection," and thought that specific characters came
first, and then natural selection came in and weeded out any
not suited to the environment.
Mr. C. F. Rousselet thought it was impossible to determine
what characters were really adaptive in the Rotifera.
Mr. D. Bryce said natural selection did not apply to his
Bdelloids, as they were all females. It was a real case of sur-
vival of the fittest. Occasionally a specific character must be
an absolute hindrance, and, in the case of long spines, must
sometimes be positively dangerous.
The President said it was very difficult to put oneself in the
position of, for instance, a sponge. But take the case, say, of a
small protuberance on a spicule, which spicule is quite sur-
rounded and embedded in the general protoplasmic mass of the
animal, and then assume another similar spicule which is without
such protuberance. It is not possible to conceive that either
the presence or absence of such a minute speck of silica could
be of any use to the individual, and yet such a difference is often
absolutely characteristic of a species. We have had instanced
this evening elaborate decoration and markings on Foraminifera.
These animals certainly cannot appreciate them visually, as they
have no organs of vision ; and, again, in life the markings would
be concealed under the usual gelatinous mass of exterior proto-
plasm. The markings are so minute that it is quite impossible
256 Proceedings of the
that the organisms could be cognisant of their existence in any
way. The markings are of such a nature as to be quite without
use to the organism, and we may take it that the possession of
one particular pattern is of just as much, or little, use to the
organism as the possession of any other pattern. Have we any
right to say that any one of the patterns is an adaptation ?
Mr. A. E. Hilton cited the case of the Mycetozoa, where the
specific nomenclature is based on minute markings on the capil-
litium. These markings are really the waste products of the
protoplasm which is purifying itself in spore-formation. It is
quite certain that the cause of the different markings must be
in the protoplasm itself. The protoplasm of different species
makes deposits in different shapes, and these must be largely
dependent on the condition of the air, as regards temperature
and moisture, at the times of spore-formation. The real seat
of the difference lies in the protoplasm itself.
Mr. W. It. Traviss exhibited and described a simple apparatus,
for use in pond-hunting, for collecting water from depths which
cannot be reached with the usual dipping-tube and stick. It
consisted of a light metal cylinder closed at one end. At the
other a light frame is fixed in a sort of handle-shape. This
frame serves as support to a stout metal rod, which is fastened
at the other end centrally to the bottom of the cylinder. On
the rod slides loosely, first, an easily fitting cap to the cylinder,
and, next, several lead discs. A string is attached to the bottom
of the cylinder — actually to an eye formed by bending the end
of the central rod which is projecting outside. Another string
is attached to the opposite end of the rod. In use the weight
of the lead discs is so adjusted that they will take the cylinder
down to the bottom, upside down and full of air, the contrivance
being lowered by the string attached to the bottom, the other
string hanging slack. On reaching the bottom, or, if desired,
some particular depth which could be marked on the string, the
second string is gently pulled, bringing the mouth of the cylinder
away from the bottom, and permitting some of the contained
air to escape. Two or three tugs at the string will allow all the
air to rush out, and at the same time fill the cylinder with
bottom-water. It will now be right side up, and the lead weights
which carried it down will keep the loosely fitting lid in position
as the apparatus is drawn up by the top string. Practically no
QUEKETT MICROSCOPICAL CLUB. 257
exchange of water takes place. Mr. Traviss also exhibited a
very convenient and portable form of siphon-strainer.
Several members testified as to the efficiency of Mr. Traviss's
apparatus, which he used at the last excursion of the Club
(June 21st).
A paper " On a New Method of Measuring the Magnifying-
power of a Microscope," communicated by Mr. E. M. Nelson,
F.R.M.S., was read by Mr. J. Grundy.
After reading Mr. Nelson's paper, Mr, Grundy offered a few
remarks of his own.
Mr. Grundy exhibited a modification of the photomicrographic
camera projection method. A light cardboard tube of about
24 in. diameter and about 12 in. in length fits loosely over the
eye-piece ; the other end is supported by a clamp-stand. (The
microscope may be in any position; inclined is most convenient.)
At a distance of about 10 in. from the lower end a circle of fine
ground-glass is fitted. This is carried in a " draw-tube," per-
mitting correction for the position of the Ramsden disc for
various eye-pieces or for different tube-lengths. If a micrometer
is placed on the stage the projected image may be observed on
the ground-glass, and the divisions gauged with dividers, and
compared directly with an ordinary rule. Mr. Grundy also
exhibited microscopes fitted with Beale's neutral-tint camera-
lucida, Ashe's modification of Beale's form, and a Wollaston
model.
The President said they were much indebted to Mr. Nelson
for his paper, and to Mr. Grundy for reading it. He had himself
very often to make microscopical measurements, and though no
doubt the method described was very good in theory he did not
know how it would work out in practice as compared with the
very simple method which he was accustomed to adopt — namely,
by drawing the object with a Beale's camera, and then in the
same way drawing the micrometer scale when placed on the
stage in place of the object. By applying these to one another
he could measure a thing in a very short time, and did not see
how he could possibly go wrong in so doing, although there might
be a slight distortion caused by the eye-piece.
A cordial vote of thanks was accorded to Mr. Nelson for his
useful paper, and to Mr. Grundy for the interesting way in
which he had brought the paper before the Club.
Journ. Q. M. G, Series II.— No. 73. 18
258
OBITUARY NOTICE.
THE RIGHT HON. SIR FORD NORTH,
P.C., F.R.S., F.R.M.S.
Bom January \§th, 1830; died October 12th, 1913.
We regret to record the death of Sir Ford North, one of our well-
known members. He died at his estate in Morayshire, in his eighty-
fourth year. He was the son of a solicitor, and became a barrister
practising in the Chancery Courts (1856). He was made a Q.C.
in 1877, and afterwards a judge, at first in the Queen's Bench
division (1881), and then in the Court of Chancery (1883), He
was a Fellow7 of the Royal Society, and a well-known entomologist.
He was elected a member of the Q.M.C. in June 1894, and in the
same year F.R.M.S. ; hewasamember of our Committee in February
1899, and was one of our Vice-Presidents from February 1901.
His unassuming and cordial manner and the interest he displayed
in the objects exhibited by members produced a feeling of friend-
ship towards him in all those who had the pleasure of meeting
him, while his patience and experience in directing a meeting
when he occupied the chair, as was frequently the case, made him
a most valuable member of the Club, and one whose loss we all
greatly regret.
259
THE PRESIDENT'S ADDRESS.
ORGANISMS AND ORIGINS.
By Prof. Arthur Dendy, D.Sc., F.R.S.
(Delivered February 2ith, 1914.)
I have in my library a copy of a posthumous edition,
published in 1732, of a remarkable work by John Ray, entitled
" Three Physico-Theological Discourses, concerning I. The Primi-
tive Chaos, and Creation of the World. II. The General Deluge,
its Causes and Effects. III. The Dissolution of the World, and
Future Conflagration." The second of these discourses contains a
very long discussion on the origin of fossils, which begins as
follows : " Another supposed Effect of the Flood, was a bringing
up out of the Sea, and scattering all the Earth over, an innumer-
able Multitude of Shells and Shell-Fish ; there being of these
Shell-like Bodies, not only on lower Grounds and Hillocks, but
upon the highest Mountains, the Apennine and Alps themselves.
A supposed Effect, I say, because it is not yet agreed among the
Learned, whether these Bodies, formerly called petrified Shells, but
now-a-days passing by the Name of formed Stones, be original
Productions of Nature, formed in imitation of the Shells of
Fishes ; or the real Shells themselves, either remaining still
entire and uncorrupt, or petrified and turned into Stone, or, at
least, Stones cast in some Animal Mold. Both Parts have strong
Arguments and Patrons. I shall not balance Authorities, but
only consider and weigh Arguments."
In the end Ray pronounces in favour of the view that the
fossils are real shells and not mere sports of nature, but he adopts
a most singular hypothesis as to how they found their way into
their present situations. It is only fair to add that this hypothesis
did not originate with him, but was the offspring of the fertile
brain of his " learned and ingenious Friend, Mr. Edward Lhwyd."*
* 1 am indebted to rny friend, Mr. A. W. Sheppard, the Editor of this
Journal, for the information that Mr. Edward Lhwyd, M.A., F.R.S. , was
keeper of the Ashmolean Museum from 1690 to 1709, and published a
catalogue of fossils in 1699.
Journ. Q. M. C , Series II.— No 74. 19
260 the president's address.
Mr. Lhwyd appears to have been much impressed by the
alleged fact that marine shells are sometimes generated in the
bodies of men and other animals, though at the present day it is
difficult enough to understand how such statements could ever
have gained credence. He observes : " For to me it appears a far
less Wonder, that Shells and other Marine Bodies should be pro-
duc'd in the Bowels of the Earth, than their Production in the
Bodies of Men or Animals at Land, And that they have been
so found, is sufficiently attested, both by Ancient and Modern
Authors, of a Credit and Character beyond all Exception."
Obviously the universal deluge could hardly be held responsible
for the occurrence of marine shells in human bodies, and there-
fore why hold it responsible for the occurrence of similar things
in the bowels of the earth %
The ingenious Mr. Lhwyd proceeds as follows : " I therefore
humbly offer to your Consideration, some Conjectures I have of
late Years entertain'd concerning the Causes, Origine, and Use
of these surprising Phenomena. I have, in short, imagin'd they
might be partly owing to Fish Spawn received into the Chinks
and other Meatus' s of the Earth in the Water of the Deluge, and
so be deriv'd (as the Water could make way) amongst the
Shelves or Layers of Stone, Earth, &c. and have farther thought
it worth our Enquiry, whether the Exhalations which are raised
out of the Sea, and falling down in Rains, Fogs, &c. do water
the Earth to the Depth here required, may not from the
Seminium, or Spawn of Marine Animals, be so far impregnated
with, as to the naked E}^e invisible, animalcida, (and also witli
separate or distinct Parts of them) as to produce these Marine
Bodies, which have so much excited our Admiration, and indeed
baffled our Reasoning, throughout the Globe of the Earth. I
imagin'd farther, that the like Origine might be ascribe! to the
Mineral Leaves and Branches, seeing we find that they are for
the most part the Leaves of Ferns, and other Capillaries ; and of
Mosses and such like Plants, as are called less perfect ; whose
Seeds may be easily allow'd to be wash'd down by the Rain into
the Depth here required."
You will note that the Deluge has not completely disappeared
from the hypothesis after all, but we may gather from what follows
that it has crept in rather by force of habit, and that the author
really relies principally upon the clouds and rain for conveying
THE PRESIDENT'S ADDRESS. 261
the " Seininium " into the crevices of the rocks where it is
supposed to develop. Indeed, he accounts in this manner for the
fact that so many of the fossil shells found in Great Britain
belong to species not found in the adjacent seas. The " Seininium"
has been brought from distant regions in the rain-clouds.
In order to make his argument more convincing, Mr. Lhwyd,
who is quite aware of some of its weakest paints, adopts the
well-known method of answering possible critics in advance.
" First" he says, "It will be questioned whether the supposed
Seminium can penetrate the Pores of Stones." To this he replies
" That it's manifest from Experience, upon which all solid
Philosophy must be grounded, that the Spawn of Animals may
insinuate itself into the Mass of Stone. And this plainly appears
from Live Toads, found sometimes in the middle of Stones at
Land, and those Shell-fish called Pholacles at Sea." In other
words, facts are facts, and there is no getting away from
them. " Secondly, 'It will scarce seem credible' that such Bodies,
having no life, should grow, especia'ly when confined in so
seemingly unnatural a Place as the Earth, &c." The answer
to this is again supplied by the voice of authority, supplemented
by an original observation on the part of the author which in-
dicates clearly enough the amount of reliance that is to be placed
upon his conclusions. " That's not so great a Wonder," he says,
" as that Shells should be sometimes generated, and even grow,
tho' they contain no Animals, within humane Bodies ; and within
the Mass of those thick Shells of our large Tenby Oysters,
which I formerly mentioned to you, as first shown me by Mr.
William Cole of Bristol, and have since observ'd myself. For
we must grant, that the Earth, even in any Part of the Inland
Country, is much fitter for their Reception and Augmentation
than humane Bodies ; especially, if we reflect, that when the
Spat or Seminium here suppos'd meets with saline Moisture
in the earth, living Animals are sometimes produced, as is before
attested." And so on to ninthly and lastly.
Evidently, in the year 1698, when this was written, the
problem of how the apple got into the dumpling had not
yet been solved by the philosophers. It is a little surprising,
however, that such views should have been accepted by so
experienced an observer as John Bay, who has been called
the Father of modern zoological science. Nevertheless, he
262 the president's address.
quotes them at length, and adds : " For my part (if my Opinion
be considerable) I think that my learned Friend hath sufficiently
proved that these Fossil-shells were not brought in by the
universal Deluge. He hath made it also highly probable, that
they might be originally formed in the Places where they are
now found by a spermatick Principle, in like manner as he
supposes. Why do I say probable ? It is necessary that at least
those, which are found in the Viscera and Glands of Animals, be
thus formed ; and if these, why not those found in the Earth ?
I shall say no more, but that those who are not satisfied with
his Proofs, I wish they would but answer them." Thus even
Kay, who was turned out of his Fellowship at Cambridge because
he refused to make a declaration with regard to the Solemn
League and Covenant demanded by the authorities, allowed
himself to be completely enslaved by his own credulity with
regard to unverified and, indeed, absurd statements as to the
occurrence of marine shells in the bodies of land animals !
I suppose that Mr. Lhwyd's quaint hypothesis was almost the
last of the many curious attempts that were made to explain
the existence of fossils before our modern views on the subject
came to be generally accepted. It affords an interesting illustra-
tion of the power of uncriticised authority to lead people astray.
Unfortunately, however, we cannot do without authority in science.
No man has either time or opportunity to prove all things for
himself. Progress is rendered possible only by the accumulation
of the labours of many workers, each relying upon his fellows.
The only safeguard against error is the free exercise of our
critical faculty and the due restraint of our natural credulity —
the original sin of the scientific man.
Let us turn now to another hypothesis. In 1875 Prof. Huxley,
in one of his extraordinarily stimulating essays,* discussed the
relation which exists between the composition of the earth's
crust and the organisms by which it has been populated. He
points out that the great Swedish naturalist Linmeus, who was
born in 1707, only two years after the death of Kay, had already
enunciated the dictum that "fossils are not the children, but the
parents of the rocks " — in other words, that rocks originate from
* "On Some of the Results of the Expedition cf H.M.S. Challenger"
1875]. Collected Essays, vol. viii.
THE PRESIDENT'S ADDRESS. 263
animals and not animals from rocks (" sic lapides ab animalibus,
nee vice versa ").
.After discussing the character of the various deposits which
form the floor of the ocean, Prof. Huxley remarks : " If the
Challenger hypothesis, that the red clay is the residue left by
dissolved Foraminiferous skeletons, is correct, then all these
deposits alike would be directly, or indirectly, the product of
living organisms. But just as a siliceous deposit may be
metamorphosed into opal or quartzite, and chalk into marble,
so known metamorphic agencies may metamorphose clay into
schist, clay-slate, slate, gneiss, or even granite. And thus,
by the agency of the lowest and simplest of organisms, our
imaginary globe might be covered with strata, of all the chief
kinds of rock of which the known crust of the earth is composed,
of indefinite thickness and extent. . . .
" Accepting it provisionally, we arrive at the remarkable result
that all the chief known constituents of the crust of the earth
may have formed part of living bodies ; that they may be the
; ash' of protoplasm/'
The view that the red clay which forms the floor of the ocean
at very great depths, and extends over an area of about fifty
million square miles, is derived from the decay of the skeletons
of Foraminifera from which the lime has been dissolved out,
has not been substantiated by later investigations. According
to Sir John Murray, the greatest authority on the subject,
it has been formed chiefly by the disintegration of pumice and
other volcanic ejecta.
It thus appears that the " ash of protoplasm '' does not play
nearly such an important part in the formation of the earth's
crust as that suggested conditionally by Huxley.
My indefatigable friend, Mr. Kirkpatrick, however, has for
some time been raking in all sorts of ashes for evidence of their
origin, and has come to the conclusion that even in the most
unlikely situations traces of simple organisms may still be
found.* He has, I fear, as yet met with but little success in
convincing his scientific colleagues of the correctness of his
observations, but his results are certainly in close agreement
with the conclusions arrived at by Linnaeus and, provisionally,
by Huxley. If these conclusions were correct we should have
-* Vide The Niimmulosphere, by K. Kirkpatrick. London, 1913.
264 the president's address.
to conceive of the solid crust of the earth as the result of a
constant interchange of matter between the living and the
dead, accompanied by physical and chemical processes of endless
complexity. We might even think of it as a huge composite
organism, alive only at the surface, but built up on the waste
products of its own collective metabolism, like a world-embracing
coral reef. I fear, however, that such a conception would be
more picturesque than accurate.
Even if we accepted such a hypothesis we should, of course,
have to remember that such a state of affairs could only have
arisen through a slow and gradual process of evolution.
Whether this process occupied a hundred million or a thousand
million years would be a matter of comparatively small import-
ance. It would be enough for our present purposes to recognise
that it must have had a beginning at some extremely remote
period of geological time, when the crust of the earth could not
by any possibility have been composed of the detritus of living
things.
It is generally admitted that there are only two possibilities
with regard to the origin of terrestrial organisms. Either thev
must have been imported from some other planet in the form
of germs, or they must have developed on the earth's surface
from inorganic materials that formed part of the earth itself.
Either event could only have taken place after the earth had
cooled sufficiently to permit of the existence of those peculiarly
unstable colloidal compounds of which living bodies are composed.
The first hypothesis has, as you are aware, received the sup-
port of no less eminent a man of science than the late Lord Kelvin,
who believed it possible that the germs of living organisms
might have been brought to the earth by meteorites. The chief
objection to this view appears to be the difficulty of believing
that any organism could withstand the heat generated by the
friction of the meteorite with the earth's atmosphere.
A modification of the same hypothesis, sometimes known as
the Theory of Panspermia, is maintained by Svante Arrhenius
and others. According to this theory, numerous living germs of
extremely minute size occur scattered through space, derived
from various planets upon which life is supposed to exist,
though at present we have no proof whatever that life does
exist upon any pi met except the earth itself. The nature of
THE PRESIDENT'S ADDRESS. 265
these invisible germs is enigmatical in the highest degree. They
are supposed to be propelled through space by the pressure of
the radiant energy streaming from the sun — and it has indeed
been demonstrated that very minute particles can be propelled in
this way by rays of light. It has been objected to this view
that no organisms could withstand the intense cold of inter-
planetary space, but we know that living organisms withstand
low temperatures much better than they withstand high ones,
and there appears to be no known minimum at which all life
is necessarily destroyed. A more serious objection is to be found
in what is known of the fatal effects of ultra-violet light rays
upon micro-organisms. At the surface of the earth such
organisms are to a large extent screened from the effects of
these rays by the earth's atmosphere, but this would not be the
case in interplanetary space.
Even if we were able to prove that living organisms first
reached the earth from some other planet, however, it would
not help us in the least to understand how they first originated.
Such a hypothesis can only serve to remove the scene of action
from the earth to some unknown sphere where the investigation
of the problem is altogether beyond our reach. We may just
as well assume at once that the first terrestrial organisms were
generated in situ upon the earth itself and endeavour to find out
how such generation may have occurred.
This brings us to our second alternative, which we may speak
of as the hypothesis of spontaneous generation, or, if we prefer
Huxley's term, abiogenesis. The discussion of this question has
unfortunately been greatly prejudiced by the hasty conclusions
of various observers who from time to time have announced that
they have actually witnessed the production of living organisms
from not-living matter, a claim which has been repeated at
intervals ever since people began to speculate on such subjects,
but which no one has yet succeeded in substantiating. I shall
refer presently to the latest efforts in this direction, but in the
meantime we must carefully bear in mind that the sudden
appearance of recognisable organisms where none previously
existed, and in situations to which no living things can have
gained access, is a very different thing from the gradual evolution
of living matter from inorganic substances by slow and imper-
ceptible steps, which are at first purely chemical and physical in
266 the president's address.
nature but gradually assume a character which distinguishes
them more or less from ordinary physical and chemical processes
and perhaps justifies us in speaking of them as vital.
That there should be perfect continuity between not-living and
living matter on the one hand, and between physico-chemical and
vital processes on the other, is clearly demanded by the doctrine
of evolution. Moreover we know that, at the present day,
inorganic matter is constantly being converted into living proto-
plasm, though only by the peculiar organising activities of
living bodies. All organisms assimilate materials derived from
their environment in order to build up their own bodies, and it
is largely this power of assimilation that distinguishes them from
bodies that are not alive. Daring life the organism conquers its
environment and appropriates such portions of it as it requires.
Death is the conquest of the organism by the environment,
accompanied by re-annexation on the part of the inorganic world
of all that the organism had appropriated during its lifetime.
The chemist has no difficulty in analysing the complex col-
loidal constituents of dead organisms into a descending series
of less and less complex substances, ending with the so-called
elements themselves. He has also, to a very great extent, accom-
plished the reverse process, and has already carried his constructive
operations as far as the synthesis of polypeptides, from which
point to the proteids themselves is but another step. He has no
right to assume, however, that when he has actually taken this
step and, further, mixed his proteids with the other substances
known to occur in living protoplasm, he will have produced
anything that is actually endowed with life. We may even say,
without much exaggeration, that the chemist, as such, has no
knowledge of protoplasm at all, for it is impossible to analyse
protoplasm while it is alive, and as soon as you kill it it ceases
to be protoplasm.
Even the simplest living things known to us behave in a
manner which cannot, at any rate in the present state of our
knowledge, be explained entirely in terms of chemistry and
physics. The living organism itself plays the part of the chemist
and the physicist, and we cannot explain the chemist or physicist
in terms of the chemical and physical operations which he per-
forms in his laboratory. Out of a multitude of possibilities the
living organism selects those materials and those modes of action
THE PRESIDENTS ADDRESS. 267
which are consonant with its requirements as a living organism,
and its power of meeting emergencies as they arise is the
measure of its power to survive. Moreover, it is able to profit
by experience and to learn how best to overcome the difficulties
presented by its environment. This being so, we are justified in
maintaining that even the simplest living thing is endowed with
a certain degree of intelligence, for intelligence is nothing but
the power of learning by experience how to perform purposive
acts.
We are not obliged, however, to suppose that the property
which distinguishes the living from the not-living — intelligence,
vitality, or whatever we choose to term it — came into existence
suddenly. It is more in accord writh our experience in other
directions to believe that it arose by imperceptible degrees,
pari passu with the evolution of organic from inorganic matter.
This, however, must not be taken to imply that there is no
essential difference between living and not-living bodies, either in
structure or behaviour. We might with equal justice say that,
because water is a compound of oxygen and hydrogen, there is
no essential difference between water and a mixture of these two
gases. We are told that to speak of the aquosity of water is
meaningless pedantry, and that to speak of the vitality of living
organisms is no less so. Of course, if such phrases are offered as
explanations of phenomena, they are entirely valueless ; but if
used merely as a kind of shorthand expression of the fact that
water and living organisms possess certain properties which dis-
tinguish them respectively from all other bodies, I see no more
harm in them than in any other technical descriptive terms. In
neither case can we supply a final explanation of the phenomena
to which we refer.
Every stage in the evolution of matter is accompanied by the
development of new properties or qualities which require the use
of new descriptive terms. As to the so-called forces which lie
behind these properties wTe know nothing. We can only classify
them, as a matter of convenience, according to the effects which
they produce. We speak of the force of chemical affinity, of the
force of gravity, of electro-magnetic force, and so on ; and if
we choose to express our conviction that none of the so-called
chemical and physical forces are adequate to explain all the
phenomena of life, there is no logical reason why we should not,
268 the president's address.
as a matter of mere convenience, speak of vital forces also.
Indeed, it appears to me more in accord with scientific method
to do this than to ignore the existence of such characteristic vital
phenomena as our own consciousness and intelligence or leave
them to be explained by supernaturalism.
After all, the quarrel between the vitalist and the mechanist is
chiefly over mere terminology. The vitalist knows perfectly well
that the organism may to a very large extent be looked upon as
a machine in which chemical and physical processes are utilised,
and the mechanist knows equally well that he cannot hope to
explain his own consciousness, and his own intelligent action,
in terms of chemistry and physics. If we recognise these two
facts it is a matter of comparatively small importance to decide
in what terms the unknown factors can best be described.
At any rate I see no reason why vitalists and mechanists should
not agree that living organisms first arose, either on our own
planet or elsewhere, by means of a complex process of physico-
chemical synthesis, in which the electron, the atom, the molecule,
the colloidal mult i- molecule and the simplest protoplasmic unit,
may be taken as representing the chief stages. This at any rate
is what we should expect from the study of those analytical and
synthetical processes with which the bio-chemist has familiarised
us, and from what we know of the process of evolution in
general.
What may be the nature of the simplest protoplasmic unit is a
question still under discussion. That it is not what we commonly
call a cell seems certain, for a cell has a complex structure which
must have been preceded by something very much simpler. The
differentiation into cytoplasm and nucleus, and, above all, the
extraordinarily complex phenomena of mitotic division, which are
observable in nearly all cases where a distinct nucleus is present,
can only have been attained as the result of a long process of
evolution. The existence of the Bacteria, in which, although
both cytoplasm and chromatin may be present, there is still no
properly defined nucleus, perhaps indicates one phylogenetic stage
through which the fully developed cell may have passed.
Possibly few biologists of the present day conceive of the most
primitive organisms as relatively large unnucleated masses of
structureless protoplasm, such as some of Haeckel's famous
Monera were supposed to be. " The entire body of these
THE PRESIDENT'S ADDRESS. 269
Monera," says Haeckel, "is throughout life nothing more than a
motile lump of slime without constant form, a small living bit of
an albuminoid carbon compound. We agree that this homogeneous
mass possesses a very complex minute molecular structure ; but
this is not anatomically or microscopically demonstrable. Simpler,
less perfect organisms are not thinkable." *
Recent researches, unfortunately, tend to throw considerable
doubt upon the existence of such Monera. It has been pointed
out that the failure to recognise a nucleus may have been due to
the imperfections of microscopical technique at the time when the
organisms in question were described. Even some of the Bacteria,
which Haeckel regarded as Monera and which are amongst the
smallest recognisable organisms, are now known, as we have just
seen, to exhibit well-marked differentiations in their protoplasm,
and many of the supposed " cytodes " or unnucleated cells, have
already been shown to possess a nucleus. With regard to others
the matter must be regarded as still sub judice.
Haeckel himself, it must be remembered, recognised the fact
that his Monera must be composed of ultra-microscopic molecules
or groups of molecules, which he spoke of as Plastidules or
Micellae, the latter term having been coined by Naegeli.
It is these ultra-microscopic and indeed purely hypothetical
particles of colloidal proteid that the modern biologist is inclined
to regard as representing the most primitive living organisms,
and Weismann has gone so far as to assign to them a definite
place in our scheme of classification, proposing for their recep-
tion the so-called family Biophoridae and identifying them with
the biophors or ultimate vital units of his well-known theory
of heredity.
It has further been pointed out that such minute particles of
living matter, far smaller than the most minute Bacteria, may be
arising all around us by so-called spontaneous generation at the
present day, without our being able to recognise the fact. It is
only when, in the course of evolution, they had become aggregated
in relatively large masses, that we could hope to see them even
with the highest powers of our microscopes. The justice of this
view might, however, fairly be questioned. When chemical mole-
cules arise in our laboratories by combination of atoms or of
* Translated from Haeckel's " Schopfungsgeschichte," Edition 9 (1898),
p. 165.
270 the president's address.
simpler molecules, they usually present themselves to us in
aggregates which are large enough to be at once recognisable,
and one would naturally suppose the same to be true of the
multi-molecules, biophors, or whatever we like to call them, of
which living matter consists. As a matter of fact, however, the
chief objection that I can see to the Monera theory is the
almost ultra-microscopical size of the simplest organisms actually
known to us. Indeed, it' we take into account the so-called filter-
passers, or Chlamydozoa, which are believed to be the germs of
certain diseases, but most of which we know only by inference,
we are justified in saying that the simplest known organisms are
actually ultra-microscopic.
It seems impossible to obtain any precise information as to the
size of the smallest particles that can be seen with the microscope.
Since this address was delivered, Dr. Spitta has been kind enough
to inform me that he has been able to see and photograph a
particle only 1/9 7,000th of an inch in diameter, and it will be
remembered that at a recent meeting of the Club Mr. Brown
claimed to have seen in the frustule of a diatom a pore the
diameter of which he estimated at 1/200, 000th of an inch. As the
filter-passing organisms are ultra-microscopic, they must be smaller
than this. Indeed, most of them have never yet been seen even
with the aid of the ultra -microscope, which, by a special method
of illumination, enables us to recognise the presence of particles
having a diameter of certainly not more than 1/2, 500,000th of an
inch and possibly a good deal less, though such particles cannot
be seen at all in the ordinary way by transmitted light.
It is only by inoculation experiments that we can prove the
existence of these ultra-microscopic parasites. Thus we are told
that if even so small a quantity as 0'005 of a cubic millimetre of
lymph from an animal suffering from foot and mouth disease
be inoculated into a healthy calf, the latter will in due course
contract the same disease, although the lymph, so far as micro-
scopic examination enables us to judge, is entirely free from
organisms.
Yellow fever, cattle plague, rabies and many other diseases are
believed to be caused by ultra -microscopic parasites. That such
diseases are due to living organisms and not to lifeless toxins is
indicated sufficiently clearly by the fact that a period of incu-
bation always follows infection, during which the poisonous matter
THE PRESIDENT'S ADDRESS. 271
increases in amount until there is enough to produce its deadly
effects, when the characteristic symptoms of disease manifest
themselves in the patient.
Buckmaster considers that most of the filterable parasites are
Bacteria, but as we know nothing of their structure it seems a
little premature to include them in any group which is based upon
morphological characters. They might be included in Weismann's
hypothetical Biophoridae, although, from the point of view of the
higher organisms, ;' death -carriers" would certainly be a more
appropriate name for them than " life-carriers."
Inasmuch as all the known filter-passing organisms are
parasitic, it might be argued that their existence implies the
pre-existence of higher organisms, and that therefore they cannot
be regarded as themselves representing the most primitive living
things. Such an argument would, of course, be entirely
fallacious. It so happens that at the present time the only
means we have of recognising the most minute of these
organisms is by their effects upon other organisms. There may
be hosts of ultra-microscopic organisms living freely on the earth's
surface which have no recognisable effects upon the higher plants
and animals, and of whose existence we therefore remain in
complete ignorance. This would be quite in harmony with what
we know of the microscopically visible Bacteria. Some of these
live freely in the soil and are able to feed upon purely inorganic
substances, while others are far more familiar to us on account
of their influence, whether beneficial or disastrous, either upon
ourselves or upon other organisms in which we happen to be
interested.
Your late President, Prof. E. A. Minchin, who speaks with
great authority on such subjects, in his last address to the Club,
devoted some time to the consideration of the question whether
the extremely minute organisms which we have be?n discussing
consist of cytoplasm or chromatin, and pronounced in favour
of the latter alternative. For my own part I must confess that
I prefer the view that at this stage of evolution the distinction
between cytoplasm and chromatin has not yet arisen, a view
which, as Prof. Minchin pointed out, is in harmony Avith the
hypothesis of the evolution of living matter from inorganic sub-
stances on the earth rather than with that of its importation
from some other planet.
272 the president's address.
It follows inevitably from the above considerations that the
frequent failure of experimenters to demonstrate the occurrence
of spontaneous generation cannot be regarded as proof that it
never takes place even at the present day ; much less as proof
that it has never taken place in the past.
The classical experiments of Pasteur, Tyndall and other
observers of the nineteenth century, so far as they related to
spontaneous generation, seem to have been for the most part
confined to the problems involved in the occurrence of organisms
in organic infusions, such infusions being the media in which
most of the known micro-organisms naturally occur and from
which they derive their food-supplies. As a result of such
experiments it is generally believed to have been demonstrated
clearly enough that if adequate measures are taken in the first
place to sterilise the culture media by heat, and in the second
place to prevent the access of living germs after sterilisation
has been effected, such infusions may be kept for an indefinite
time without any organisms making their appearance in them,
and, consequently, without undergoing putrefaction. It is also,.
I believe, generally supposed, though with little justification,
that this conclusion applies to all culture media whatever,
whether organic or inorganic.
One observer, however, Dr. Charlton Bastian, whose earlier
experiments were contemporary with those of Pasteur and
Tyndall, and who has recently been again engaged in similar
investigations, has consistently maintained a different view.
His earlier experiments, like those of other observers, were con-
ducted with organic infusions, or with artificial nutrient solutions
such as ammonium tartrate or other salts of ammonia. The
positive conclusions arrived at by experiments with organic
culture media may be considered to have been completely nega-
tived by the general experience of bacteriologists during the
subsequent forty years.
With regard to the origin of living things from the inorganic
world, however, the negative results obtained by properly con-
ducted experiments with organic infusions are of comparatively
little value. If spontaneous generation takes place at all at
the present day it probably takes place as it must have done
at some time in the past, when no organic bodies existed to
supply food for the first living things. In other words, we
THE PRESIDENT'S ADDRESS. 273
should not expect to be able to observe spontaneous generation
in infusions of organic matter, but should conduct our experiments
with purely inorganic substances.
Dr. Bastian's a priori position is a very strong one. If
spontaneous generation took place once upon the earth's surface-
there is no known reason why it should not take place to-day,
while the actual existence of countless hosts of extremely
primitive organisms alongside the most highly finished products
of organic evolution certainly seems to support the view that such
primitive forms are constantly arising from inorganic constitu-
ents and emerging from the obscurity of their birth only when
they have reached a stage of evolution at which they are capable
of appealing directly or indirectly to the human senses.
Dr. Bastian employed for some of his recent experiments* a
very dilute solution of sodium silicate, to which was added either
a minute quantity of pernitrate of iron, or a small quantity of
phosphoric acid and ammonium phosphate. He joints outr
however, that the sodium silicate is a variable commercial product
and attributes to this fact certain otherwise unaccountable
variations in the results obtained. The experiments were there-
fore repeated with pure colloidal silica in place of the sodium
silicate, and positive results were again secured.
The method of procedure is as follows. The solution to be
experimented upon is hermetically sealed up in a glass tube
and heated to about 130° C. for ten minutes or more. After the
lapse of a few weeks, or in some cases months, during which time
the sealed tubes have been exposed to ordinary atmospheric
conditions, they are found to contain living organisms, Torulaey
Bacteria and even moulds being present in varying quantities.
Dr. Bastian claims that these organisms have arisen in the
tubes by spontaneous generation, or, as he terms it, Archebiosis.
He supposes that the living matter probably originated in
the first place in the form of ultra-microscopic particles, but
maintains that in the course of a few weeks or months these
particles developed into the organisms finally found.
To a certain extent these results are, as I have already pointed
out, in accord with purely a ])riori expectations, but in other
respects they appear improbable to the last degree. Most of the
* For a full account of these experiments the reader is referred to
Dr. Bastian's recent book on The Origin of Life. 2nd Edition, 1913.
274 the president's address.
organisms produced are of well-known types, and one of the
moulds formed appears to be a Peniciliium producing spores
in the ordinary way. I must confess that I myself find it
impossible to believe without much stronger evidence that such
comparatively highly organised beings can have been evolved so
rapidly from ultra- microscopic germs. We are accustomed to
think of evolution as a very slow and gradual process, and we
know that Bacteria, Torulae and moulds may be cultivated for
an indefinite period without undergoing any recognisable change ;
indeed many industries, such as brewing, wine-making and
cheese-making, depend for their very existence upon this
fact. May we suppose that all these organisms have reached
the limits of their evolution? If so we have the answer to
the question, why have they remained stationary while other
organisms have developed into the higher forms of plants and
animals ? If, however, we are asked to believe that the Bacteria
and Torulae are stages in the evolution of the moulds, why does
not this transformation manifest itself in our everyday experience ?
Dr. Bastian himself, it should be observed, is a convinced
upholder of the doctrine of heterogenesis, or the sudden appear-
ance of one kind of organism as the offspring of another, but
it may be doubted whether any other living biologist holds similar
views.
Again, are we to believe that such organisms arise in nature
under many different conditions and from many different
mixtures of chemical compounds, or are we to believe that
Dr. Bastian has accidentally, and almost at the first attempt,
hit upon just the right materials and the right conditions for the
production of well-known living things 1 His own observations,
if correct, show that the experimental solutions may be varied
within wide limits, but this is hardly what we should expect if
the origin of living things is to be regarded as a mere stage in a
series of chemical and physical processes. Another criticism
of these results may be based upon the fact that the materials
employed do not (unless accidentally) contain all the necessary
ingredients of protoplasm. Carbon is apparently entirely
wanting, and we must either suppose that it is accidentally
present in minute but sufficient quantities as an impurity, or
else that it can, as Dr. Bastian actually suggests, be replaced,
to a greater or less extent, by silica in his organisms. It has
THE PRESIDENT'S ADDRESS. 275
been suggested that the colloidal character of the silica employed
is especially favourable to the evolution of living matter, but
unless the organisms are largely composed of silica, which is
highly improbable, it is difficult to see exactly what the colloidal
silica has got to do with their origin, unless, indeed, it may be
supposed to act as a catalytic agent.
Altogether I think we may fairly say that the acceptance
of Dr. Bastian's results would involve us in so many difficulties
that it is preferable at present to believe that there has been
some error in his mode of procedure, some unsuspected loophole
through which contamination of his preparations has taken
place.*
The whole problem looks surprisingly like a modern version
of the old story with which we started. The question " What
was the origin of the fossils in the rocks ? " is replaced by the
question " What was the origin of the organisms in the glass
tubes 1 ': We have seen how, in the former case, certain
statements, made apparently in perfectly good faith, led to
entirely wrong and absurd conclusions. We are all agreed
now as to how the fossils got into the rocks, but I am not aware
that anyone has ever succeeded in explaining the mystery of
how the marine shells got into the human body, or even how
the toads got into the stones in which they were alleged to have
been found. .No one, however, whose opinion is worth con-
sidering, believes that they were generated there. All are
agreed that there must have been something wrong with the
original statements, and there we must be content to leave
it. It is doubtless premature to say that Dr. Bastian's
organisms are merely toads in stones, but I do not see much
to choose between the difficulties of explanation in the two
cases. The decision must be left to the future, and in the mean-
time we may console ourselves with the reflection that science
* Since this address was written Dr. Bastian has published a lengthy
communication in Nature (January 22nd, 1914) in which he tells us that his
results have been confirmed by four other observers, two in America and
two in France. The American observers say, however, " We have no sug-
gestion to make other than your interpretation, and, indeed, we desire to
be entirely non-committal as yet." Prof. Hewlett, the well-known bac-
teriologist, writing at the same time, states that, although he has made
similar experiments, he has not yet been able to confirm Dr. Bastian's
results.
Journ. Q. M. C, Series II.— No. 74. 20
276 the president's address.
cannot be infallible, but can progress only by a process of natural
selection, in the course of which one hypothesis replaces another
in the struggle for existence. The buckets in which we draw up
truth from the bottom of the well are very small and very leaky,
and a good deal that is not truth finds its way into them before
they reach the surface. Fortunately the impurities, even if they
cannot be eliminated at once, sooner or later sink to the bottom
and leave the water clear.
Journ. Quekctt Microscopical Club, Scr. 2, Vol. XII., No. 74, April 1914.
277
A CHANGER FOR USE WITH SUB-STAGE
CONDENSERS.
By S. C. Akehurst, F.R.M.S.
Bead October 2Mb, 1913.
Figs. 1 and 2.
Petrological microscopes have been fitted in various ways to
arrange for a quick change of sub-stage condenser, and I have
frequently felt the need of a similar method applied to a
Fig 1.
biological microscope. I found the revolving nose-piece to carry
three condensers did not work satisfactorily, therefore adapted
the principle employed in the sliding objective changer to the
sub-stage fitting, and found this enabled me to get an easy and
rapid change of condensers.
The scheme consists of a metal slide 2| x If, with bevelled
edges, on which the condenser is mounted, and, when necessary,
a throw-out arm for stops, and an iris diaphragm. Two D-shaped
278 S. C. AKEHURST ON A CHANGER FOR SUB-STAGE CONDENSERS.
metal plates, the flat sides of which are set 1| inch apart, form
a groove for the slide to work in. These plates are screwed to a
metal collar, the diameter of which is such as to allow the slide-
condenser changer to be fitted to any microscope that has a sub-
stage made to the R.M.S. gauge. Fig. 1 shows a plan of the
slide changer in position, while fig. 2 gives a sectional elevation
along the line A B, fig. 1. When three, or more, condensers are
used it is desirable to have each mounted on a separate slide ;
but when only two condensers are used, one slide may be
sufficient, as the optical parts can be made interchangeable.
Fig. 2.
When the slide with condenser has been pushed home, a screw,
working through one of the plates, holds this firmly in position.
This changer does away with the necessity of a throw-out
sub- stage, and any variation of centrality in the condenser can
be adjusted by the centring screws in the regular way.
To rack down the sub-stage fitting, withdraw and insert a new
slide, are all the movements that are required to obtain a change
of condenser, and this can be effected as readily as a change of
objective on a revolving nose-piece.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 74, April 1914.
279
A TRAP FOR FREE-SWIMMING ORGANISMS.
By S. C. Akehurst, F.R.M.S.
{Bead October 2H(h, 1913.)
Fig. 3.
Simply stated this is an arrangement which cuts off the retreat
of the creatures after they have been attracted into a small
receptacle by light.
The first trap I used was made of glass — in two pieces. The
top is funnel-shaped, and holds about 5 ounces of water. This
is attached to a horizontally-placed cylinder, 1 inch in diameter,
and 1| inch long — the whole being mounted on a stem and foot.
Into the cylinder is fitted a glass spigot, which has been ground
in to avoid water passing. There is a hole at the bottom of the
funnel flask which allows free access of the water to a small well
in the glass spigot.
When the trap is working, this well opens immediately under
the hole at the bottom of the flask, and into this the organisms
can enter freely. When desiring to fix the catch, give the spigot
a slight turn — the mouth of the well then presses against the side
of the cylinder and the contents become locked in.
To set the trap, fill the flask with pond water, cover the entire
funnel-shaped flask with some light-proof material, and direct all
the light that can be gathered by a bull's-eye on to the cylinder
winch contains the glass spigot. Any swimming phototactic
organism in the water will at once react and pass into the well,
which is brightly illuminated — usually 10 to 15 minutes is
sufficient to allow for this, but longer time can be given if
necessary. Give the spigot half a turn, and, as already explained,
this locks the creatures in the well. The water can then be
poured off from the flask, the spigot withdrawn, and the rotifers —
or whatever may have been trapped in the well — can be taken
up with a pipette and transferred to the slide for examination.
After the first catch has been taken the trap can be set again and
a second lot secured. Work can therefore be carried on without
interruption or loss of time until all the water has been dealt with.
Should there be any sediment, this can be allowed to settle and
then trapped off before any attempt is made to catch the organisms.
There is difficulty in obtaining this trap made in glass ; I have
therefore worked out another in metal (fig. 3). This consists of
a round box, 1 inch in depth, 3| inches in diameter — the top and
bottom slightly convex — mounted on a tripod. A hole in the
bottom allows the water to pass through a short tube, which is in
three sections, the first part metal, the second rubber and the
third glass. A pinch-cock can be applied to the rubber con-
nection, which will prevent water passing when the glass tube
has been removed for examination of contents.
280 S. C. AKEHURST ON A TRAP FOR FREE-SWIMMING ORGANISMS.
I have departed from the funnel shape — making the metal
box to hold the water almost flat, which will allow any sediment
to settle at the bottom. If the water is very muddy, a cork can
be fitted into the outlet hole and left until the debris has settled
— first filling the tube with clean pond water.
If the cork is carefully removed, very little, if any, dirt will
pass down the tube. Should some slip by, this can be trapped
off, the tube refilled with water, when a perfectly clear gathering
can be secured.
A strainer is provided, to be used, when necessary, for removing
Fio 3.
larvae or any of the entomostraca. It is important, that as much
light as possible should be concentrated on the glass tube.
To arrange for this a bi-convex lens 1| inch diameter, silvered on
one side and mounted in a metal holder with a movable support
allowing it to be tilted at an angle, is placed under the tube, light
from a bull's-eye condenser is received by the lens and a bright
beam passed up the tube. This method of transmitting the light
is very effective, and the trap in consequence acts more rapidly
and effectively than when the bull's-eye condenser only is em-
ployed. The lens — placed in position — is shown in the illustration.
Journ. QueketL Microscopical Club, Ser. 2, Vol. XII. , No. 74, April iyi4.
281
AN IMPROVED FORM OF CHESHIRE'S APERTO-
METER.
By Edward M. Nelson, F.R.M.S.
(Exhibited and described by James Grundy, F.R.M.S., October 28th, 1913.)
Fig. 4.
Of the value of Mr. Cheshire's form of Apertometer there can be
no doubt. The aim of Mr. Kelson has been to enable the N.A.
of an objective to be read on the Apertometer with greater ease
and accuracy.
Distinctness and clearness of reading have been effected by
APERTOMETER OlAGRAM
/S. - 1 >nch.
(ffcfj)
Fig. 4.
increasing the number of marked values of N.A. from 9 to 22,
without the confusion that overcrowding of the lines would entail.
To accomplish this, short arcs of circles are used instead of whole
circles. A valuable property of these is the clear visibility of the
ends or edges of the arcs ; they are seen more distinctly than
complete circles would be. The contrast between the white
ground and the short black lines favours this.
The exterior edges of the arcs denote the N.A., and thus give
most convenient, accurate and definite positions for reading.
282 E. M. NELSON, AN IMPROVED FORM OF CHESHIRE'S APERTOMETER.
The first or lowest marked value is 0'05 N.A., and the values
increase by increments of 0'05 up to 0'5 N.A. From 0*5, the
values increase by 0*033 up to 0*9 N.A.
The apparatus consists of an Apertometer diagram (fig. 4)
printed on a small card about the same size as Mr. Cheshire's
form, another card of explanations and instructions, a cubic inch
of wood and a metal diaphragm with a hole not more than
1*25 mm. in diameter. Mr. Nelson lays some stress on the hole
in the diaphragm being not more than 1'25 mm. in diameter.
He says: "If the hole is larger than that, some objectives,
especially low powers, will read a great deal too high. And
accuracy is, relatively, more important with the small apertures,
because — for example — an error of O'Ol or 0*02 will make a far
greater percentage of difference than it would with, say, the
N.A. of an oil-immersion objective. If 1*25 and 1*27 be com-
pared with the N.A. 0*11 and 0*13 of a 3-inch objective, the
actual difference between the two pairs of values is 0*02 in each
case, but the percentage difference with the higher N.A. is only
1*6 as compared with 18 in the case of the low values."
In this connection, Mr. Nelson has made another important
remark, namely, " The working aperture is larger than the
correctly measured true aperture, so that low powers resolve more
than they are entitled to theoretically. This is probabhy due to
the practically enlarged aperture caused by the rolling motion
of the eye from side to side."
It will also be noticed that the diaphragm to be used with the
apertometer is made convex on one side, and if the convex side
is put into the larger aperture of an eye-piece — or other —
diaphragm, it rests steadily in position.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII. , Ko. 74, April 1914.
28
n
TWO SIMPLE APERTOMETERS FOR DRY LENSES.
By Frederic J. Cheshire, F.R.M.S.
{Read October 2$th, 1913.)
Figs. 5 amd 6.
In dealing with questions of apertometry it is very important to
inquire, in the first place, as to what order of accuracy it is
desirable to work. No useful purpose would be served by giving
a carpenter a foot-rule, divided to hundredths of an inch, with
which to measure the length of a plank. The measurement,
if made to such an order of accuracy, would be useless and
meaningless.
Prof. Abbe, in " Some Remarks on the Apertometer" {Journal
of the Roy. Jlic. Soc. 1880, p. 20), after stating that the error of
measurement in his well-known apertometer is limited to about
| per cent., goes on to say that "an exactness of reading
to this extent is evidently more than sufficient. An unavoidable
amount of uncertainty resulting from the nature of the object,
and many other sources of slight error, will always limit the
real exactness of observation beyond 1 per cent, of the unit,
different observers and different methods of equal reliability
being supposed. In low powers slight variations in the length
of the tube, in high powers slight alterations of the cover-
adjustment, will admit of much greater difference than the
error of reading will introduce. It should be observed that
in high-angled objectives the aperture has not the same
value for different colours, owing to the difference of focal
length (or amplification), even in objectives, which are perfectly
achromatic in the ordinary sense. In the case of very large
angles, the aperture, angular or numerical, will be greater for
the blue rays than for the red, generally by more than i per
cent. Last, not least, there is no possible interest, either
practical or scientific, appertaining to single degrees, or half
284 F. J. CHESHIRE, TWO SIMPLE APERTOMETERS FOR DRY LENSES.
•degrees, of aperture angles ; for no microscopist in the world will
be able to make out any difference in the performance of objec-
tives as long as the numerical apertures do not differ by several
per cent., other circumstances being equal."
" For these reasons I consider all attempts at very accurate
measurements of this kind to be useless."
No one, probably, is likely to have the temerity to question
the authority of Prof. Abbe on such a question as Apertometry,
so that we can accept his limit of 1 per cent, with confidence.
Fig. 5 shows a plan of a form of apertometer for dry lenses
which for simplicity in use and for the accuracy of its results
probably leave nothing to be desired. A strip of vulcanite A *
is so divided that the distance D of any line from the zero of the
scale is given by the equation
D = 2 A tan (sin-i n.A.)
set out in this Journal for April 1904 (Ser. 2, vol. ix. p. 1), in
the article on " Abbe's Test of Aplanatism, etc." The graduations
are marked with the corresponding N.A. values for a value of A
equal to 25 mm. In use the apertometer is placed upon the
.stage and the object plane of the lens to be tested adjusted at a
height of 25 mm. above the plane of the scale. The upper focal
plane of the objective is then observed in any known way and the
apertometer adjusted on the stage until the inner edge of the
fixed white block B is seen on one edge of the objective opening.
This adjustment effected, the sliding white block C is slid along
the strip A until its inner edge is seen on the opposite edge of the
objective opening to that on which the block B is just seen.
The N.A. value found opposite to the inner edge of the block 0
on the scale is that of the lens tested.
The graduations from 0 to 0*9 N.A. proceed by steps of 0*02
and from 0-9 to 0*96 N.A. by steps of 0-01.
Fig. 6 shows a modification of the form of apertometer
described in my original paper in 1904. I have substituted for
the concentric circles there shown curved lines which project
optically into the upper focal plane of the lens being tested as a
number of equi-distant straight lines of equal thickness. The
projected image of the apertometer scale is thus a simple linear
* The right-hand end is shown broken off.
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286 F. J. CHESHIRE, TWO SIMPLE APERTOMETERS FOR DRY LENSES.
scale upon which N.A. values can be read directly. The scale
runs from 00 to 0*9 N.A. by steps of 0*05, i.e. the divisions
starting from the centre have the values 0, 0'05, 0"10, 015, 0-20,
etc., of N.A.
The short curved lines of the scale should strictly be hyperbolas,
but such curves are very difficult to draw accurately, and it was
not until my son, Mr. R. W. Cheshire, suggested to me that they
might be replaced by arcs of circles with curvatures equal to
those of the corresponding hyperbolas at their vertices that the
apertometer described became a practical construction.
I may, perhaps, be allowed to avail myself of this opportunity
to say that in my opinion there are several objections to
Mr. Nelson's form of the Apertometer which was introduced
by me in 1904. These may be briefly indicated. In the first
place, no advantage can result from the use of the outer edges
of the lines, instead of the middles, as is usually done, as the
part of the lines from which distances and therefore NA.'s
must be estimated by eye. Further, in Mr. Nelson's form the
thickness of the lines varies in different parts of the diagram,
and has no assigned or stated thickness in terms of N.A. This,
I think, is a fatal defect, because when the thickness of a line
has a N.A. value of 0-02, say, such thickness, especially when
dealing with low-power lenses, provides an invaluable standard
of reference when estimating by eye N.A. values intermediate
to those represented on the scale.
In apertometers of the kind in question the further the sub-
division of the scale is carried the greater must be the complexity
of the image presented to the eye — the advantage of one is
balanced by the disadvantage of the other. Possibly, however,
most people would prefer the simplicity of a diagram with the
larger divisions to the optical Hampton-Court-maze necessitated
by the smaller ones.
Joum. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 74, April 1914.
287
A VARIATION OF CHESHIRE'S APERTOMETER.
By M. A. Ainslie, R.N., B.A., F.R.A.S.
.(Read October 2Sth, 1913.)
Figs. 7 and 8,
Experience in the use of both the original forms of Cheshire's
Apertometer, and the modification thereof recently introduced
by Mr. E. M. Nelson, has revealed one or two difficulties in
connection with the reading of the instrument — that is, if any
accuracy in the second place of decimals is required — and the
present instrument is an attempt at removing these.
The first difficulty is due to the fact that in Mr. Cheshire's
instrument we have to interpolate or estimate between two
divisions on a scale, one of which is not visible, being outside
(apparently) the margin of the back lens of the objective, This
renders the estimation of the second place of decimals in the
N.A. uncertain, and although Mr. E. M. Nelson's modification
of the original instrument is somewhat better in this respect —
yet the very means adopted to improve the reading, namely,
the introduction of a large number of additional circles — is
likelv to confuse the diagram and bewilder the observer.
In either the old form or the new of Cheshire's instrument,
a count has to be made of concentric circles ; a thing which,
simple as it may seem, is peculiarly liable to confuse the eye ; so
that it is only after counting several times that one feels certain
that the number is, say, eight and not seven. In the present
instrument a totally different method of reading is adopted ; the
diagram is simplified, and the estimation of the second place of
decimals is merely the estimation of the point where a spiral
curve cuts the margin of the back lens of the objective, referred
to two points, one on each side, where radial lines cut the
same.
The instrument, which consists, in the form for dry lenses,
288 M. A. AINSLIE ON A VARIATION OF CHESHIRE'S APERTOMETER,
of a card diagram placed on the stage, is constructed as follows-
(% 7):
A series of radial lines are drawn from a common centre,
making equal angles with one another ; the precise number is-
immaterial, but it has been found convenient to divide the circle
into sixteen equal parts. One of these (preferably that lying^
horizontally) is selected as a zero, and points are marked off
along the others at distances equal to a constant length (usually
25 mm., or 1 inch) multiplied by the tangent of the semi-angle
of aperture ; i e. the tangent of the angle whose sine is the-
numerical aperture. This is done for every (H of N.A., and
a spiral curve drawn through the points thus obtained ; this.
Fig. 7.
curve being repeated, turned through 180°. The curves are
shown with fair accuracy in fig. 7.
The diagram is used precisely as the Cheshire Apertometer :
either the objective is focused on the upper surface of a cube of
wood as in the Cheshire instrument ; or else a pinhole in the
centre of the diagram is focused, and the body racked back
25 mm., or 1 in., this being measured easily enough with a
scale. This latter method is preferable for objectives of high
aperture. A |low-power eye-piece is employed. On examining
the Ramsden disc with a hand lens (a watch-maker's eye-glass
does well) the appearance in fig. 8 is seen, and the method of
estimating the value of the N.A is fairly obvious ; we have only
to start from the zero and count in the direction of the spiral,
M. A. AINSLIE ON A VARIATION OF CHESHIRE'S APERTOMETER. 28i>
(H for each radial line passed over ; the second figure is found by
estimating the position between two adjacent radial lines of the
point where the spiral cuts the margin of the back lens. In
tig. 8, for example, the N.A is about 0-73.
The procedure is the same with the form suited to immersion
lenses ; the upper surface of a plate of glass is focused, and the
diagram is balsamed to the lower surface. It might be pre-
ferable to have 12 radial lines instead of 16, and read like
a clock ; this is a matter for experiment.
Of course the value of the radius vector of the curve for
a diagram in optical contact with glass will not be quite the
same as before ; instead of r = C tan <£, where sin <£ = N, we
8
Fig. 8.
shall have r = C tan <£' where /x sin <£' = N\ but the principle
is the same. »
The equation to the curve presents some interesting features;
aO
where C is the distance of the diagram
it is r = C—r_
V 1 — a202
from the lower focal plane of the objective and a is a constant
depending on ll and on the number of radial lines in the circle ;
for 16 radial lines, and /x = 1 (dry form), a = ^— . The radius
representing N.A. = I/O is obviously an asymptote to the curve ;
in the case of the glass form, N.A. = /x will be the asymptote.
It is of interest to note that the same curve will serve for any
refractive index of the medium beneath which it is mounted : if
290 M. A. AINSLIE ON A VARIATION OF CHESHIRE'S APERTOMETER.
we change the refractive index from 1 to ju, we merely have to
close up the radial lines in that ratio, leaving the curve unaltered.
For instance, if we had 16 radii for the dry form we could use
the same curve, but with 24 radii, for a plate of glass of
fx = 15.
In practice the instrument proves of great utility, and very
reliable and easily used. All that is necessary is to be accurate
in centring ; this is easily seen to be correct when the reading of
each end of the spiral is the same.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 74, April 1914.
291 AfclC
ON THE DISC-LIKE TERMINATION OF THE
FLAGELLUM OF SOME EUGLENAE.
By James Burton.
(Bead November 25th, 19130
About two years ago, one of our members — Mr. Ellis — was
exhibiting here living Euglena viridis. During the evening the
creatures, presumably affected by the light, heat and confine-
ment of the life-slide, threw off their flagella ; it was perhaps a
preparatory step to encystment, or even to their death, under
the unnatural conditions of their environment. In the field of
the microscope there were numbers of these organs floating
free, and in the case of many of them, if not quite the ma-
jority, they were terminated by what appeared to be a small
disc or bulb. We were greatly interested in the phenomenon,
and decided to investigate it. Mr. Ellis soon after wrote a
letter to The English Mechanic, describing what he had seen, and
inquiring if any one else had had a similar experience. There
were no very definite answers, no one claiming to have noticed
this occurrence before. In his letter he says :
" On turning on the one-sixth, something quite out of the
ordinary — at least, to me — was seen in the shape of minute
transparent discs, each with a long, thick, but motionless fla-
gellum, and apparently associated with the resting Euglenae,
around which they appeared most plentiful. For some time I
was puzzled to account for these objects, until, noting the
obvious similarity in length and thickness between their flagella
and those of the motile Euglenae, I became convinced they were
one and the same, they having been thrown off* bodily by the
exhausted Euglenae, and not retracted — as is usual, I under-
stand." . . . " Now here comes the difficulty : What is the little
disc to which the flagellum is attached ? Is it the ' knob-like
inflated distal extremity ' of a flagellum belonging to 'an interest-
ing local variety of E. vi?'idis' described by a writer in Science
Gossip for October 1879, and referred to by Saville-Kent on
p. 382 of his ' Manual of the Infusoria,' and illustrated on
Jourx. Q. M. C, Series II.— No. ~±. 21
292 J. BURTON ON THE DISC-LIKE TERMINATION OF THE
PI. xx. fig. 29 ? " Saville-Kent says, in the paragraph referred to :
" An interesting local variety of E. viridis has been recently
described by Mr. M. H. Robson, of Newcastle-upon-Tyne, in
which the distal extremity of the flagellum presents an inflated
knob-like aspect, as shown at PI. xx. fig. 29. Possibly such
modification of this important organ represents a phase pre-
liminary to its entire withdrawal, and antecedent to the
entrance of the animalcule upon the encj7sted or resting stage."
In Science Gossip (1879) there are several letters about the
phenomenon, one on p. 231 by Mr. Robson, with the original
drawing from which Saville- Kent's figure is taken, and also two
other forms of Euglenae with identical organs. Referring to
them, Mr. Robson says: "These may be of interest, as I, at all
events, have not met an observer who has previously noted this-
peculiarity." In a letter on p. 136 another writer mentions a
case where in a large number of Euglenae " the flagellum was in
each case bulbed." And he draws the singular conclusion that
these were not true Euglenae, but suggests they may have been
a larval form of the rotifer Hydatina senta. In a letter, p. 159,.
Mr. Robson writes of E. viridis and its " sucker bulb," and of the
existence of " the bulb siphon, sucker, or whatever it is." On
p. 256 there is a letter from Mr. George headed, " E. viridis and
its bulbed flagellum," and he makes reference to the fact that
" on one occasion, whilst closely watching the contortive move-
ments of a full-grown specimen, I was much surprised to see the
little animal ' bite off",' if I may so term it, the flagellum, which
immediately floated away." It is clear at least from all this that
observers a good many years ago saw the structure, and that it
created a good deal of interest and some speculation as to the true
interpretation of the appearance.
Now, to return to Mr. Ellis's question, " What is the little
disc " attached to the distal end of the flagellum of some
Euglenae ? After some considerable attention to the subject,,
and observation of many examples, I have come to the conclusion
that there is no disc, no bulb or sucker, or anything of the kind
at the end of the flagellum. The appearance which has given
rise to the idea can be correctly accounted for in another
manner. I have often seen the disc since Mr. Ellis first called
attention to it, but do not remember ever seeing it on a flagellum
in active use by a healthy Euglena ; in fact, it is almost impos-
FLAGELLUM OF SOME EUGLENAE 293
sible to see the flagellum at all when the creature is in full vigour
— it is then usually being lashed about, and is bent and twisted in
all directions. It will be noticed that Mr. Ellis only claims to
have seen the disc when, for some reason, the organ to which it
was attached was thrown off.
He says : " Out of all the numberless motile Euglenae which
were swimming about amongst their resting kindred, not one was
seen with a flagellum having a knob at its free extremity."
Neither do I think any of the writers in Science Gossij) dis-
tinctly claim to have seen it on a healthy, active animal. But
when the flagellum is thrown off — " bitten off," as has been
described — or when the Euglena is killed by a careful application
of iodine, it is not at all infrequent, and I have seen it on speci-
mens from many different localities.
It happened that since I thought of bringing the subject
before you I was looking over, for quite another purpose, a slide
of Euglenae mounted in April 1911. I there found several
instances of discs still attached. Some creatures, and some
Euglenae at all events, occasionally carry the flagellum stretched
out rigidly in front, with a small portion of the distal end thrown
into a coil or spiral form, usually rapidly moving. Now if the
creature were killed with the organ in that position, or for any
reason threw it off, it seems to me very probable that the coil —
there might be but one turn in it — would present just the
appearance we have had referred to as a disc or bulb, and that,
consisting of protoplasm, it would be very likely to adhere where
touching another part, and so retain its form as a circle. With
the use of an immersion objective and careful illumination, it has
seemed to me possible to make out a part of the circle as being
thicker or darker than the rest, owing to the thread overlapping
at that point. It must be remembered that we are dealing with
a very small and very transparent structure, not easy to demon-
strate correctly. Moreover, among the others, killed by iodine
or mounted, it is easy to find specimens with the flagellum much
twisted and thrown into " kinks." So that there are often small
circles at the sides instead of at the end of the thread, and
although these have just the same appearance as those at the
end, I do not think any one would suggest that it is likely a disc
or bulb would occur in such a situation, to say nothing of the
im probability of there being more than one, and these often on
294 J. BURTON ON THE FLAGELLUM OF SOME EUGLENAE.
opposite sides. These would be put down at once as loops — or
kinks — and I believe the so-called terminal disc or bulb is of the
same nature, but it is more striking and more deceptive, owing
solely to its position. When I told Mr. Ellis of the conclusion I
had come to, he was at first disinclined to accept it, but after-
wards, I think, did so fully. If I am right, the subject is merely
an instance of correct observation but incorrect deduction from
it — in fact, an error of interpretation, quite a well-known occur-
rence to microscopists ! Perhaps, indeed, the matter would hardly
justify particular reference to it, had not the figure and the note
read appeared in Saville-Kent's Manual — a work whose value to
us all gives it an importance and authority which must be my
excuse.
Joura. Que/cett Microscopical L'lub, Ser. 2, Vol. XII , A'o. 74, April li'14..
205
ON THE MEASUREMENT OF THE INITIAL MAGNI
FYING POWERS OF OBJECTIVES.
By Edward M. Nelson, F.R.M.S.
{Read November 25th, 1913.)
Fig 9.
The majority of uiicroscopists only concern themselves with the
total magnifying power of their microscopes, but some wishing to
probe further into matters want to know the initial power of their
objectives.
The initial magnifying power, m, of an objective is -7-, but the
focal length (f) of an objective is a very difficult thing to measure
directly. Usually it is found by an indirect method of measuring
the magnifying power, for, as above, — = /.
Probably the best way of measuring the focal length by the
indirect method is to project the image of a measured object,
placed 100 inches from the stage, and to measure the diminished
image at the focal point of the objective by means of a microscope,
fitted with a screw micrometer ; the magnification, m, thus
obtained will give the focal length with great accuracy, for
f — ~ —z. As the numerator is 100, the result can be found in
nt 4- 'Ji
a reciprocal table, without the necessity of doing a division sum.
Simple as this seems, it is however a troublesome thing to do ;
but by the method here described the initial power, and hence the
296 E. M. NELSON ON THE MEASUREMENT OF THE
equivalent focus of a microscope objective, can be quickly and
easily measured.
The apparatus required is a stage micrometer and a screw
micrometer with a positive eye-piece. With a tube of a length
as described below, the interval of two divisions of the micro-
meter scale on the stage is read on the drum of the eye-piece,
and this reading will be the initial magnifying power of the
objective.
The only difficulty here is the determination of the proper
tube length. The tube length is to be measured from the
web in the eye -piece to the end of the nose-piece of the
microscope.
The formula for the determination of the tube length is
15 \/ - -f- 0335, where p is the nominal initial power. Example:
V
The initial power of a half-inch is required. The nominal
power of a half-inch is 20, which is p, then 15 A/ — + 0*335 =
15v/0-385 = 15 x 0'62 = 9*3 inches tube length.
The tube must be drawn out until the web is 9-3 inches from the
nose-piece, and, with the half-inch on the nose-piece, two y^^ths
of an inch divisions on the stage micrometer are spanned by the
webs. The drum then is read, say, 22*4, and this is the initial
power of that half-inch, without any further calculation; its focal
length is ip^ ov Q'^Afi inch.
In case the nominal initial power is unknown, it is first deter-
mined with, say, a 9^-inch tube, the value thus found is inserted
in the equation and the measurement made again with the
correct tube length. All powers of quarter-inch and less focus, all
Zeiss's apochromats of whatever focus, and other makers' apoch-
romats, require a 9-inch tube.
INITIAL MAGNIFYING POWERS OF OBJECTIVES.
297
For lower powers the accompanying table, computed by the
above formula, gives the necessary tube length.
It must be noted that it has been assumed that the screw
micrometer with the positive eye-piece is an English one, with
50 threads to the inch, but if it is a Continental one, with a
millimetre thread, a millimetre stage micrometer must be used,
and the proper number of divisions measured. If it is found that
the magnification is so high that two divisions cannot be spanned
by the micrometer webs, then obviously one division is measured
and the reading is doubled.*
TABLE.
0, objective ; N, nominal power ; T, tube length in inches.
0
N
T
O
N
T
o
12-3
1
10
9-9
3
3-5
11-8
3
4
12
9-7
4
11-5
2
3
15
9-5
4-5
11-2
1
2
20
9-3
2
5
11-0
4
25
9-2
5-5
10-8
1
7J
30
9-1
6
10-6
35
9-05
1|
7
8
9
10-4
10-2
100
1
40
9-0
Let me again impress upon microscopists to measure, or get
measured, the optical indices of their objectives. The optical
1000 N.A.
index is
m
Photographers have the same thing in their
//4, //16, etc. No photographer would think of paying as much for
a lens of f/lQ as he would for one, of similar focus and qualitv, of
fji) then why should a microscopist? A microscopist, for example,
The foci of a large number of all sorts of microscope objectives, which
had been previously accurately determined by the long method, were
remeasured by this new short method ; the results obtained were so
satisfactory that now only the short method is used.
298 E. M. NELSON ON THE MEASUREMENT OF THE
buys a T*oth objective of 0"65 N.A. Here an optical index of 26-0
is implied ; when he gets home he measures it and finds it |rd of
055 N.A. with an optical index of only 18*3, or 30 per cent. less.
This is not an exceptional case, but one which unfortunately
exemplifies the usual practice. Messrs. Zeiss have for long set an
excellent example by never sending out lenses below either their
catalogued N.A. or shorter foci. I have measured scores of them
and have found their optical indices often in excess, and seldom
if ever in defect.
[The method of determining the focal length of an objective,
by the indirect method from the magnifying power, may not be
A
t
B
L too inc\e& _^
i
c
Mr
r
s
Fig 9. — Diagram to show Relative Positions of the Apparatus.
M — Microscope tube. P> — Objective.
A — Screw micrometer. C — Objective to be measured, in substage.
S — Microscope stage and micrometer.
quite clear, hence the following particulars from notes received
from Mr. Nelson may be useful. His own words are practically
as follows: The microscope is placed horizontally; a low- power
objective, 3, 2, or 1| inch, according to circumstances, is placed
in position ; screw-micrometer eye-piece ; the objective to be mea-
sured is placed in substage, with its front lens facing the stage.
A card cut to the pattern as shown in figure (fig. 9) is fixed by
means of a clip in front of the window : the card should be
placed at the exact measured distance of one hundred inches
from the stage of the microscope.
INITIAL MAGNIFYING POWERS OF OBJECTIVES. 209
The stage micrometer is placed on the stage, and the constant
of the screw-micrometer determined. The focus of the micro-
scope is not to be disturbed, but, by means of substage focusing,
the lens to be measured is racked up until the image of the card
is sharply focused. Then one of the sides of the card is spanned
by the webs of the eye-piece micrometer, and its size measured
and the magnifying (or rather diminishing) power found : then
._ 100
• ~~ m + '2'
Of course, the idea of the 5 inches is that the reading is
doubled, and then 10 -t- x (say), gives the magnification, m, which
can be found from reciprocal tables, as well as the value of —
^ ' 1,1 + T
It is not difficult, but a little more trouble, to make the calcu-
lations without tables.
For the benefit of photomicrographic members, the following
is quoted from a note by Mr. Nelson. " This method will
measure the foci of large photographic lenses. In that case
,_ 100 _ 100 „
m + 2 (m + If
" This second term is only necessary when f is large compared
with one hundred inches ; for microscopic lenses it is not wanted.
The whole can be determined from reciprocal tables without
putting pencil to paper." The tables referred to are those of
Barlow, published by Messrs. E. & F. N. Spon.
The screw-micrometer eye-piece is, perhaps, a drawback. Mr.
Nelson says, "An ordinary screw-micrometer with a negative
eye-piece is no good for lens measurements ; the eye-piece must be
of the Ramsden type, and it is very doubtful if any ordinary
ruled glass micrometer eye-piece would be sufficiently accurate.
A screw-micrometer is necessary for both the methods described
in the paper."
300 E. M. NELSON ON INITIAL MAGNIFYING POWERS OF OBJECTIVES.
It will be noticed that Mr. Nelson lays stress on what he has
named the Optical Index ; but perhaps it is less apparent that
this paper on the magnifying power of objectives, and his com-
munication to the last meeting on their aperture, are quite
closely related to the Optical Index — in fact, they deal with both
the values involved in the formula for the Optical Index of an
, . .. Numerical Aperture x 1,000
objective = — —A ^ .
Magnifying .rower
A general way of expressing the meaning of the Optical Index
of an objective is that it is the ratio of its aperture to its
power. — J. Grundy.]
Joura. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 74, April 1914.
301
SOME OBSERVATIONS CONCERNING SUB-STAGE
ILLUMINATION.
By S. C. Akehurst, F.R.M.S.
(Bead January 27th, 1914.)
Plates 20-22.
The accepted method, and the one generally used, for sub-stage
illumination is that known as the solid cone of light, controlled,
within certain limits, by the iris diaphragm. Another form — that
is, annular light — is occasionally used, but is not considered by
many microseopists to be of value for critical work.
Both these forms of illumination are too well known to need
detailed explanation. The textbooks, however, have very little
to say either for or against the latter method, excepting Cross and
Cole, 3rd edition, where a definite statement in favour of annular
light is to be found. I cannot do better than quote this : " Stops
can be further used for strengthening the contrast in the image
with large cones of illumination and objectives having high
apertures. This method does not minimise in any way the
effective working of the objective, for, with objectives of large
aperture, rays may be present which only impart brightness to
the field, but do not contribute to making visible the fine detail
upon the object. If less than half of the lateral spectra are seen
on looking down the tube at the back lens of the object glass with
a striated object in focus, then the central portion of the direct
beam or central disc has no lateral image corresponding to it in
the portions of the spectra that are visible. Under these circum-
stances, that central portion of the central disc in no degree
contributes in enabling the detail to be seen, but only produces a
haze ; by blocking it out the haze is removed and there is a great
302 S. C. AKEHURST ON SOME OBSERVATIONS CONCERNING
improvement in the resulting definition." Mr. J. W. Gordon's
opinion is that when a suitable stop is employed in the sub-stage
condenser there is no objection to using annular light with an oil-
imniersion objective of high numerical aperture. It is, however,
necessary that the outer zones of the objective used should be
well corrected. His own method of blocking out the central
beam is to use a stop over the eye-piece — and this is fully described
in the Journal R. M. S., February 1907. On the other hand,
Carpenter does not entirely agree that annular light is permissible.
Quoting from the seventh edition, he says, " If it is required to
accentuate a known structure, such as the perforated membrane of
a diatom, it can be done by annular illumination, which means
the same arrangement as for dark-ground but with a stop insuffi-
ciently large to shut out all the light. This method is not to be
recommended when a structure is unknown, as it is also liable to
give false images."
Mr. Nelson has also expressed himself against annular light,
stating that whilst strong resolution of diatoms is obtained by
this method of illumination it also gives rise to spurious images.
The subject of sub-stage illumination is a large one, and I am
only dealing with one phase of it, viz. annular light produced by
a reflecting condenser, to be used in conjunction with an oil-
immersion objective, for resolving the fine structure of diatoms
and displaying stained bacteria.* When a wide-angle refracting
condenser is employed, with stop to produce annular light, trouble
arises through chromatic aberration, which is especially noticeable
when an objective of high aperture is used. This dispersed colour
is objectionable, as it operates against a pure image being formed,
and is also detrimental to obtaining faithful records by photo-
graphy. Much has been undertaken to demonstrate that, in
practice, light from a condenser exhibiting chromatic aberration
* A slide of Tubercle bacilli was exhibited illuminated with annular
light, showing that the reflecting condenser works well with small stained
objects in addition to diatoms.
SUB-STAGE ILLUMINATION. 303
does not prevent good work being accomplished. On the other
hand, I believe the reduction of chromatic dispersion to a minimum
leads towards an ideal system for critical work.
The question now arises, if annular light is employed with
objectives of high aperture, how is the trouble arising through
chromatic aberration to be avoided. I suggest reflected, instead
of refracted, light being used. I came to this conclusion after
makincr a number of observations with a Leitz concentric reflect-
ing condenser. This condenser has two reflecting surfaces, one
convex and the other concave, and, as the rays are brought to a
focus by reflection only, there is no chromatic dispersion, and
spherical aberration is reduced to a minimum. The elimination
of spherical aberration, however, is not a matter of importance.
This was pointed out to me by Mr. J. W. Gordon, who has very
generously allowed me to make use of his remarks on this point.
He says: "Light from the periphery of the condenser may
exhibit defects due to spherical aberration. This light, on reach-
ing the object, sets up a new impulse, and the rays emerging from
the object, and travelling towards the eye, will, in any plane con-
jugate to the plane of the stage, appear free from the original
defects of spherical aberration — just as if they had started from
an independent source. No false images would, therefore, arise
from this cause in the image plane when light is used from a
sub-stage condenser that has not been corrected for spherical
-aberration." It should be carefully noted that this reflecting con-
denser was produced to obtain dark-ground effects, and was never
intended to be used in the manner I have employed it — that is, in
conjunction with a TV inch oil-immersion objective without a funnel
stop to reduce the IS". A. of the objective. In its present form the
reflecting condenser I have passes too much light. The results
obtained, however, were sufficiently striking to arrest attention
when resolving fine structure of various diatoms. The transverse
striae of Amphlpleura pellucida in monobromide of naphthalin
were displayed. In realgar the same details were strongly shown,
304 S. C. AKEHURST OX SOME OBSERVATIONS CONCERNING
and when the mirror was slightly tilted, if the diatom was a
suitable one. it was resolved into dots. A good image of the
rosettes on Coscinodiscus asteromphcdus was obtained, which
stood a high-power eve-piece well. With the mirror slightly
tilted, the faintly marked transverse striae were visible on Cymato-
pleura solea — also an excellent black-dot image was displayed of
Xo.ck'da rhomboid.es, SurireUa gemma and Pleurosigma angu-
IcUuin. On examining a strewn slide of Xacicula r~homboid.es
in realgar I found a specimen of Pinnularia nobilisl On tilting
the mirror and obtaining oblique light the costae were filled with
dots. Particulars of this were forwarded to Mr. Nelson, who
replied as follows: "Mr. Merlin and I have seen the structure
on Pinnularia to which you refer. It was demonstrated upwards
of twenty years ago by H. Gill, who tilled up the apertures in
diatoms with platinum — some of these specimens I have still." I
am pleased to be able to give this report, as it helps to dispose of
the idea that might arise that the dots displayed were probably
due to false images, brought about by using annular light.
The opaque lines on an Abbe test plate were well defined, and
an excellent rendering of stained bacteria, such as Tubercle bacilli,,
was obtained. In all the tests referred to the following combina-
tion was used : Incandescent gaslight, Nelson stand condenser,
Leitz concentric reflecting condenser and tiuorite, TVth inch oil-
immersiun objective N.A. 1*35, Wiukel complanat eye-piece, and
Wratten B screen.
During the autumn of 1913 Mr. O'Donohoe became interested
in this reflecting condenser, and he spent an evening with me
examining some of the test objects referred to ; and afterwards
kindly undertook to see if any results worth attention could be
obtained by photography when using this type of condenser. He
was successful in getting a record of the dots on Pinnularia.*
I am very much indebted to Mr. O'Donohoe for the ready
manner in which he undertook the work of testing the condenser,
* T. A. O'Donohoe : "An Attempt to Resolve Pinnularia xobilis,'' p. 309.
SUB-STAGE ILLUMINATION. 305
and for the photographs which illustrate this paper ; and you
will agree with me that without these records my remarks con-
cerning the value of reflected annular illumination would have
been much less convincing.
Summary of the Advantages in using Annular Light
produced by reflecting condenser.
(1) When employing an achromatic condenser excess of light
is reduced by closing the iris diaphragm. This involves a sacrifice
of the numerical aperture, and, therefore, loss of resolution.
With the reflecting concentric condenser there is no loss of high-
angle rays, the excess of light being modified by stopping out a
portion of the central or dioptric beam; the fullest possible
advantage can, therefore, be taken of the numerical aperture of
the whole optical system.
(2) Chromatic dispersion being entirely eliminated, a pure
image is obtained.
(3) The absence of colour in the field admits of critical work
being done by photo-micrography.
(4) When necessity arises to search a slide for minute striae,
or other fine structure, it is immaterial in which direction across
the field the striae appear — they are resolved.
(5) The simple construction of this type of condenser admits
of it being produced at about half the cost of an achromatic oil-
immersion condenser ; and whilst it can only be employed with a
Y2-th inch oil-immersion objective in the manner already described,
yet it gives excellent dark-ground effects with all powers from
Ygth to ^th inch.
One defect — if defect it can be called — is that, in its present
form, there is no method of controlling the light passed by altering
the size of the stop. It is just possible means can be devised to
allow of this being done.
In my opinion there appears to be room for a reflecting con-
306 S. C. AKEHURST ON SOME OBSERVATIONS CONCERNING
denser to be used with high-angled oil-immersion objectives, even
though the field for its usefulness may be limited.
1 hope the photographs illustrating this paper will prove of
sufficient interest to stimulate further investigation into the
value of annular light, and to demonstrate what limits, if any,
should be put upon its use.
Descriptions of Plates.
Plate 20.
Figs. 1 to 7 are illustrations of various figures of the spectra
of Pleurosigma angulatum as seen at the back lens of an oil-
immersion objective with the diatom in focus — an achromatic
condenser, with and without stop, and reflecting condenser being
used. Pigs. 1 to 3 are of no special interest just now — most of
you are familiar with these diffraction spectra, varied according
to the diameter of the opening in the iris diaphragm.
Fig. 1 shows result obtained with the diaphragm almost closed.
Fig. 2 the diaphragm is opened so that one-third of the back
lens is in shadow. The details of the diatom are hardl)T per-
ceptible, being flooded out by excess of light.
Fig. 3. The iris is closed, until two-thirds of back lens is in
shadow. In this position, with the spectra just touching the
edge of the central beam of light, the best resolution of Pleuro-
sigma angulatum is obtained.
Fig. 4 shows the spectra obtained when a large spot is used.
The six diffraction spectra forming the symmetrical image should,
however, be slightly moved from the centre outwards to reduce
the diameter of the hexagonal spot in the centre, which in the
drawing is a little too large. In this instance insufficient light
was passed, and an unsatisfactory image of the diatom was dis-
played. My next spot being too small, the picture of the spectra
obtained is as shown by flg. 5. Here Ave have six dark cuspidate
forms, disposed as a six-pointed star, the intermediate spaces
being filled with a diffused light, the whole figure being some-
SUB-STAGE ILLUMINATION. 307
what ill-defined. This effect was due to an excess of light ; by
slightly closing the iris diaphragm the light was reduced, and we
have the result as shown in fig. 6 — the symmetrical design well
defined on a black ground, and just a glimpse of another portion
of the spectra at six points round the shadow caused by the partly
closed diaphragm. With the spectra showing, as illustrated in
fig. 6, I obtained the best definition of Phurosiyma angulatum
with achromatic condenser and spot.
Fig. 7 is the record of the spectra obtained of the same diatom,
using the reflecting condenser ; the similarity between the figures
7 and 5 is noticeable.
My reflecting condenser — to work at its best when using it for
annular light — requires the light cut down until a crisp image is
shown of the spectra as at fig. 6.
Fig. 8 represents the rulings on an Abbe test plate, as displayed
by TV inch oil-immersion objective and reflecting condenser. The
position of the light bars is to be noted : there are six — those at
the top and bottom are not quite fully displayed. On first
examining the back of the objective I observed the two rows
of six white dots, as shown at fig. 9. At another examination —
the light probably being more central — I found an almost com-
plete circle, as at fig. 10, made up of ten white clots on each side
and a thin streak of light at the bottom. I have not yet been
able to put forward a suggestion as to how these are formed.
I have, however, included them in my record, as they may be
of some interest.
Plate 21.
Fig. 1. Nitzschia linearis x 2,500, showing the white-dot image.
This photograph was taken with a highly corrected oil-immersion
condenser and axial illumination.
Fig. 2. Nitzschia linearis x 3,000, this time showing the
black-dot image. This photograph was taken with reflecting
concentric condenser.
Journ. Q. M. C, Series II.— No. 74. 22
308 S. C. AKEHURST ON SUB-STAGE ILLUMINATION.
Both these pictures were taken by the same man, using the
same objective, diatom and illumination — the only difference
being in the condenser used. Regarding this matter, Mr.
O'Donohoe writes as follows : " I was never able to see the
black-dot image when using my ordinary oil-immersion condenser,
hence was much surprised to find that the reflecting concentric
condenser showed the black dots beautifully. This and the
Amphipleura show that the reflecting condenser is a better re-
solver than my ordinary oil-immersion condenser and axial
illumination.
Fig. 3. Amphipleura pellucida x 2,000. This photograph was
taken to demonstrate the usefulness of annular light when
searching a slide for fine structure. The diatoms are at right
angles to each other, and both resolved. Had light in one
azimuth been employed, such as one gets with an achromatic
condenser, and quarter-moon stop, only one would have been
resolved, viz. the diatom with striae at right angles to the
direction of the beam of light.
Fig. 4. A record of Surirella gemma x 2,000. This was
taken with the reflecting condenser. The black dot is shown,
and at the same time the ribs are resolved into dots.
Plate 22.
Fig. 1. Navicida rkomboides x 1,500, taken with the re-
flecting condenser.
Fig. 2. Pinnidaria nobdis x 2,500, showing the costae filled
with dots. Taken with the reflecting condenser.
Journ. Quekett Microscopical Club, Scr. 2, Vol. XII., No. 74, April 1914.
Journ. O.M.C.
Ser. 2, Vol. XII., PI. 20.
WEW OF BACK LENS' OP OBJECTIVE
•j <
PL EURO SIGMA. >- HG\J LATUM I hi FOC
JCATIC
CONDENSE ~
*fl r
ACHROMATIC
C0Ni)£NS£R
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STOP
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REFLI
CONDE.NSER
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PLATE
C. H. Caffyn, photogr.
Journ. Q.M.C.
Ser. 2, Vol. XII., PL 21.
T. A. O'Donohoe, photogr.
Resolution with Annular Illumination.
Journ. Q.M.C.
Sen 2, Vol. XII., PL 22.
T. A. O'Donohoe, phologr.
Resolution with Annular Illumination.
o
09
AN ATTEMPT TO RESOLVE AND PHOTOGRAPH
PINNULARIA NOB I US.
By T. A. O'Doxohoe.
(Read January 21th, 1914.)
Most microscopists are acquainted with the little diatom called
Pinnidaria nobilis, which, on the test slides of twenty diatoms
mounted by Moller and Thum, takes the second lowest place,
with striae numbering from 11,000 to 12,000 to the inch.
It is just because it occupies such a lowly place that it is
passed over with contempt as being worthy of the notice only
of the babes and sucklings of microscopy who find themselves
in possession of a 2-inch or 1-inch objective.
Such was my own feeling towards it until quite recently,
when Mr. Akehurst showed me by resolution into dots that it
deserved a better fate, and invited me to resolve and photograph
it, if I could, and for this purpose he, at the same time, lent
me a realgar mount and the reflecting dark-ground condenser
of Leitz. I have since learnt that an objective and illumination
which, without any manipulation, showed me at once the striae of
Nitzschia linearis, Frustulia saxonica, and Amphiplewa pellucida,
and the very distinct black dots of all the other diatoms on
Thum's test plate of 30 forms, failed completely in inducing the
Pinnidaria nobilis on the same slide to yield up its secrets. So
that the diatom to which almost the lowest place is assigned
by the mounter is, in fact, by far the most difficult to resolve.
Examined with a drv lens of N.A. 0-85 and direct cone of
light, we get an image in which on each side of the raphe
are seen two zig-zag lines running from end to end and dividing
the linger-like bands into three series — or each band into three
compartments. This is all that can be seen with a dry lens.
Now using a Zeiss 2-mm. apochromat N.A. 1*3, and Watson's
Holoscopic immersion condenser, and finding a central cone of
light unavailing, I inserted the crescent stop in the condenser,
and proceeding as if I were resolving the striae of Amphiphura
pellucida, I succeeded in getting an image which shows what one
310 T. a. o'doxohoe on pin nul aria nobilis.
must call the costae, broken up into three parts, with very fine
lines between them. It may be seen that the middle parts of
the costae are in the sharpest focus because they represent the
highest of three distinct planes. Now if this interpretation be
correct, the structure of this diatom is very complex, as there
would be three planes on each side of the raphe, and the planes
on the one side would coincide with those on the other only when
the diatom was perfectly flat on the cover-glass —a very un-
likely case.
I now tried to resolve the costae, with the result as shown
[here an image was projected on the screen], which reminds one
of the bones of a skeleton's hand.
There remained the resolution of the very fine lines between
the costae, probably into dots. After trying to do this many
hours without any success I substituted Mr. Akehurst's dark-
ground condenser for the Holoscopic, with the result that, after
considerable manipulation I was able to get the photograph here
reproduced. (See PI. 22, fig. 2.) This shows at least partial
resolution on both sides of the raphe.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 74, April 1914.
311
NOTES.
ON A METHOD OF MARKING A GIVEN OBJECT FOR
FUTURE REFERENCE ON A MOUNTED SLIDE.
By James Burton.
{Read November 25th, 1913.)
Most likely all of us at times have come across some particular
object on a mounted slide which we have felt we should like to be
able to find on another occasion ; perhaps some special diatom on
a strewn slide, for instance. Now there are several methods of
doing this, and a little piece of apparatus is sold by the opticians
which marks a circle round an object first found under the micro-
scope. But perhaps with the majority the necessity does not
occur often enough for it to be worth while to keep a special tool,
and the little dodge, if I may call it so, which is here described
can be carried out without any other instrument than those we
most of us already have and use. If the object to be marked is
sufficiently large for recognition under a moderate power, such as
can be obtained with a hand lens or dissecting microscope, the
matter is very simple. First find the object, then with a fine
camel-hair or sable brush carefully place a dot of water-colour
over it large enough to be seen with the naked eye, set it on one
side to dry ; when dry, put the slide on the turn-table with the
dot accurately in the centre and turn a small ring round it with
any dark cement you may have in use; when this is hard, which
will depend on the kind of cement used, the water-colour can be
removed with a damp brush, and the cover can be carefully
cleaned with a piece of soft rag.
If the object, however, is too small to be readily recognised
without a high power, as, of course, is usually the case, for
it is not necessary to mark anything but minute objects,
a rather more complicated variety of the same plan should
be adopted. Again first find the object with a suitable
power, such as a | inch or ^th inch, and let the specimen be as
312 J. BURTON ON A METHOD OF MARKING A GIVEN OBJECT.
accurately placed in the centre of the field as possible ; then sub-
stitute for this power, preferably a water- immersion objective,
say TV^h, put on the front lens a small drop of water and care-
fully focus. It is necessary that the slide should not be moved
after contact is made, as it is desirable to keep the drop of water
as small as possible. When the object is recognised and is in the
centre of the field, raise the microscope tube rather sharply and a
small circular spot of water will be left on the cover-glass right
over the desired place. Now stain this spot with water-colour as
in the other case — 1 always use the carmine kept for feeding
infusoria, etc., but any colour will do. When this is dry the
slide may be roughly examined and the object will be seen
through the coat of colour, which for this purpose should not be
too thick. If it be rightly placed, proceed as before, putting a
fine ring of suitable size round the spot with some dark cement,
and when this is dry carefully clean off the colour, and the
arrangement is complete. Water-immersion lenses are not very
commonly used now, and if the microscopist does not happen to
possess one, an oil-immersion may be used instead, but obviously
it must be used with water, not oil ; but this will give a sufficiently
good image for our purpose, which is merely to recognise the
specimen for marking, not to examine it. If an oil-immersion be
not available, any close- working objective, say gth inch or even
-g-th inch may be used, but it is necessary that the front lens be a
small one, so that the spot of water placed by it should be as
local as possible.
There are, of course, some difficulties ; the chief is, that objects
mounted in glycerine — as mine usually are — are somewhat
liable to move if at all roughly handled, and may work
out of the circle ; but with balsam or glycerine jelly mounts, or
even a shallow glycerine one, there is little danger of this. If a
turn-table is not in the outfit of the experimenter, a sufficiently
good circle may be drawn by hand, or a line drawn to indicate
the position, or, as has been suggested, the barrel of a mapping
pen or similar object may be used. But the first great difficulty
is always to indicate the exact spot it is desired to mark, particu-
larly if the object is a very minute one, and that is got over with
facility by the method indicated.
M. DRAPER, A LIVE BOX FOR THE OBSERVATION OF INSECTS. 313
A LIVE BOX FOR THE OBSERVATION OF INSECTS
AND SIMILAR OBJECTS.
By B. M. Draper.
{Read December 23rd, 1(J13.)
This live box, which was worked out for me by Mr. Angus,
displays satisfactorily, with superstage illumination, under the
lowest powers, large creatures such as house-flies. It is not
meant for pond-life.
It is of the simplest description, being really nothing but a
transparent chamber of the shape and size of a small pill-box.
The body is made of a short piecs of glass tube of any size de-
sired, say, one-third of an inch deep by two-thirds in diameter ;
this is cemented to a 3 X 1-inch slip. The lid, which is loose,
is a circular plate of glass of rather larger diameter than the
body. In the lid, near its circumference, and at equal distances
from each other, are fixed three short pins, projecting downwards,
so as to clasp the outside of the body and thus keep the lid in
position. The little collars by which the pins are fixed in the
lid rest on the rim of the box, so as to prevent the lid itself
from touching. The crack thus left gives enough ventilation.
The depth of the box can be varied by means of a false bottom,
preferably opaque.
This box serves well for the exhibition of a fly in the act of
feeding. If a little syrup is put on the inside of the lid of the
box, the sucking surface of the proboscis may be seen in action.
DARK-GROUND ILLUMINATION WITH THE GREEN-
HOUGH BINOCULAR.
By B. M. Draper.
{Bead December 23rd, 1913.)
The Greenhough pattern of binocular consists, as is well known,
of two separate microscopes, one for each eye, with paired
objectives of very low power. Like other binoculars, it is
particularly well suited for use with dark-ground illumination,
and a good way of getting the dark ground with its higher
powers is to put a stop behind the condenser.
314 B. M. DRAPER ON THE GREENHOUGH BINOCULAR.
As, however, the front lenses of the twin objectives stand out
some distance on either side of what would be the optic axis of an
ordinary microscope, the stop has to be correspondingly broad
from side to side ; otherwise direct rays would enter the objectives
and would spoil the dark ground at the sides of the field. But it
is not necessary that the rectangular diameters of the stop should
be equally great ; on the contrary, if an ordinary circular stop be
used, some rays are needlessly obstructed. On trial, a double
or twin stop, corresponding with the twin objectives, gave much
better results. This stop consists of two small circular patches
placed side by side in the same plane, and touching each other r
so as to form a figure of eight. It is used behind the condenser
in the same way as an ordinary circular stop, and with almost
equal ease. It is only necessary to be careful that the two circular
jDatches shall be placed horizontally, i.e. so as to be opposite the
two front lenses of the twin objectives. This position can easily
be secured by arranging the stop in the carrier approximately and
then, whilst watching the object, shifting the whole condenser
round in its sleeve until the best effect is obtained. A standard
low-power condenser such as Swift's " Paragon," with its top lens
off, gives very satisfactory results. The twin and the ordinary
circular patterns of stop were compared experimentally by using a
condenser fitted with two stop carriers, one behind the other, so
that either stop could be used separately, or both together. The
twin stop used by itself gave a good dark ground. The circular
stop was purposely chosen too small to give a good dark ground ;
there was light at the sides of the field. Nevertheless when the
circular stop was turned in above the twin stop whilst the object
was under observation, there was a marked drop in the brightness
of the image. This loss of light was due almost entirely to the
circular stop, not to the clear white glass on which it was mounted,
since it was found that the interposition of such a. piece of glass,,
even when rather dirty, made very little difference to the light.
Evidently, therefore, the circular stop, though too small in one
direction, was too large in the other, and kept out some rays
which might safely have been admitted. Of course if the circular
stop had been large enough to darken the background when
used by itself, the loss of light would have been still more
noticeable.
E. M. NELSON ON AMPHIPLEURA LINDHEIMERI. 315
AMPHIPLEURA LINDHEIMERI.
By Edward M. Nelson, F.R.M.S.
(itearf December 23rd, 1913.)
Half a century ago Xavicula rhomboides was the accredited test
for the best microscope lenses. This was the common " English "
rhomboides, which has about 72,000 to 73,000 striae per inch ; it
was also known as the Amician test. About the seventies
iV. rhomboides was discovered in America. This was a coarser
form, having some 60,000 striae per inch, consequently any 90°
| inch N.A. 0*71 would resolve it readily. In those days there
were no cheap apertometers to be had, so testing an objective
merely meant a measurement of aperture by resolving striae
on some diatom by means of oblique light in one azimuth. We
now know that the feat can be accomplished by a very badly
corrected objective.
The new coarse American rhomboides became very popular, and
diatom dotters and brassey glassites simply revelled in it.
History has, however, repeated itself, for as time went on lenses
improved, and both the coarse and fine rhomboides failed as tests
for high powers, so others had to be found to fill their place.
Amphipleura pellucida became the test for immersions, while
A. Lindheimeri was used for dry lenses. As A. Lindheimeri has
about 7 ",000 striae per inch, it is a very suitable test, with oblique
light from a dry condenser, for lenses of the 7a type.
This wTas the favourite test of the late Lewis Wright, who
mentions it in his excellent book on the Microscope. But now
another Lindheimeri has been discovered in Spain, and as it is a
coarser variety, it is necessary to distinguish between these forms
when quoting the Lindheimeri as a test. The new Lindheimeri
has 67,000 striae per inch, and therefoi e is easier to resolve than
the old English rhomboides ; a | inch, or 8 mm., will very nearly
resolve it — in fact, they do so in patches; a Powell 100° | inch
of 1S75, which would fail on an English rhomboides, resolves it
easily.
The new Lindheimeri can be recognised at once by its very long
terminal nodules, the terminal nodule being one-third of the whole
length of the valve, while in the old form it is only one-fifth.
316 E. M. NELSON ON AMPHIPLEURA LINDHEIMERI.
The length-breadth ratio in the new form is 7*5, and in the
old 8-5.
The conditions here are therefore opposite to those we found in
Naviada rhomboides,* for those with the greater ratio had the
coarser striae, but in this case they have the finer.
If we divide the ratio by the number of striae in T— ff ^th of an
inch we shall obtain a numerical index of about 1*1. Thus :
Old Lindheimeri : Ratio 8*5, striae 7*7, index l'l.
New Lindheimeri : Ratio 7 '5, striae 6*7, index l'l 2.
Amphipleura pellmida follows much the same rule,for "resolvers"
who understood the subject sought out wide valves, i.e. those with
a small ratio.
* Journal Q.M.C., vol. xi. p. 97, 1910.
Jovrn. Qv.ekclt Microscopical Club, Ser. 2, Vol. XII., No. 74, April 11)14
317
SOME NOTES ON THE STRUCTURE OF DIATOMS.
By N. E. Brown, A.L.S.
(Read March 2ith, 1914.)
Plate 23.
These notes are offered to the Quekett Microscopical Club, not
-with the anticipation that, with the exception of one point, the
-expert will find in them much that is not already known, but
because my interpretation of certain familiar features is different
from that which is usually accepted and may therefore be of
some interest in promoting thought in another direction.
Structure of Pirmuiaria spp. — Although P. major and allied
species are familiar to all microscopists and their structure is
■doubtless well understood by experts, yet the description of it in
English text-books is by no means satisfactory and also does not
seem to be too well known. A good description with figures by
Floegel will, however, be found in the Journal of the Royal Micro-
scopical Society, 1884, vol. 4, p. 509, t. 8 (Pinnularia).
I regard P. major as a very simple type, perhaps one of the
simplest types of diatom-structure. In front view the valve pre-
sents a series of transverse markings on each side of the raphe,
which are so easily seen that I believe few diatom- dotters pay much
attention to them. These markings consist of linear cavities or
canals in the valve, separated from one another by very thin par-
titions, and each of them is provided with a comparatively large
linear-oblong opening on the inner side, communicating with the
interior of the diatom ; it is evident that during life the protoplasm
enters and fills these cavities, and therefore they must play an
important part in the life-economy of the diatom. The motions of
n living diatom are not only interesting to watch, but are puzzling
to everv one who has observed them. It is no uncommon thing to
see a Pinnularia or other free-swimming diatom apparently take
hold of a particle of dirt and move it to and fro along its sides or
upper surface. On one occasion I saw P. major with two frag-
ments of dirt, one on each side of it near the margin ; both pieces
"were moved forwards and backwards in the same direction for
-a time and then suddenly they were moved each in a different
318 N. E. BROWN ON THE STRUCTURE OF DIATOMS.
direction, and finally one piece was passed from one side completely
round one end to the other side, where, upon meeting the other
piece of dirt which was moved towards it, the invisible hands
moving the dirt lifted it up and placed it upon the other piece of
dirt and held it there, both together being then moved up and
down as before. Now this and other movements I have witnessed
could only have been made at the will of the diatom, and in my
opinion must have been controlled by living matter extruded from
the interior of the shell, and therefore there must be openings
through which the interior is in communication with the exterior
other than at the raphe, where, as is well known, a crest of proto-
plasm extrudes, which, from measurements I have made, varies
from l/14,000th to l/3,000th inch in depth and l/6,000th to
1/1. 800th inch in breadth. Feeling convinced of this, I sought
for several years for evidence of pores in Pinnularia without
finding the slightest trace of them, and all authors I have con-
sulted state that there are no openings in the valve of Pinnularia
other than at the raphe. With respect to diatoms in general,,
in the 8th edition of The Microscope and its Revelations (1901),
p. 590, it is stated, " We have in fact no positive demonstration
of the existence of special apertures communicating between the
outside and inside of the cell."
However, some four years ago I obtained a sample of the
Chei-ryfield diatomaceous deposit, and upon mounting some of it
in picric piperine, found that it contained four or five species of
Pinnularia, on one of which I at last saw indications of the pores.
I had so long sought. This species is one of the smallest in the
material and the only one on which I have been able to see any
indication of pores. They are only to be seen when the outer
surface of the cavities is accurately in focus and the light central,
and are so minute and crowded that they appear like a single
dusky beaded line extending all the way along the centre of the
cavity, and they do not appear to be present at any other part. At
any focal plane below the external surface, such as when the large
opening into the interior of the diatom is in view, they cannot be
seen. When viewed from the inside of the valve they are scarcely
visible except where seen through the large opening of the cavity
into the interior. Although a distinct bead-like appearance is just
discernible, the pores are so closely placed that neither I nor the-
friends to whom I have shown them, have been able to see them
N. E. BROWN ON THE STRUCTURE OF DIATOMS. 319
as distinctly separate dots. It is only on this particular species,
the name of which I do not know, that I have been able to discern
these pores. Upon the far larger P. major and P. nobilis I can-
not see any trace of them, although I do not doubt that they
exist in these species also, but are probably smaller than in the
species in which I discovered them. As seen by myself and
friends at a magnification of 3, COO diameters they are as repre-
sented at PI. 23, fig. 13.
Upon the sides or girdle of all species of Pinnularia are to be
seen two slender lines, which under sufficient magnification are
seen to be composed of a multitude of short transverse lines ; in
P. major these average about 60,000 to the inch. These lines I
have failed to resolve into distinct dots, although Mr. E. M.
Nelson (Journ. Q.M.C., Ser. 2, Vol. VI. p. 144) states that he
has done so, and I do not doubt his statement. But at the same
time I very much doubt if the clots of which these transverse
lines are composed are real pores. The lines are so easily seen
that they evidently are much too coarse for pore structure, and
my interpretation of the structure of these two lines on the
girdle of Pinnularia is, that each line consists of a multitude
of very minute cavities placed side by side, similar to those seen
in the front view of the valve, and that when they are truly
resolved each cavity will be found to have a minute pore at the
centre or a row of pores along the central line of each cavity or
clear space between every pair of short transverse lines.
It may be well to state that there are sometimes appearances
to be seen on the walls of the cavities of P. major and P. ?iobilis
which may easily be mistaken for rows of pores. As I have
seen them, they appear like two rows along each cavity, but
upon moving the mirror slightly these rows move also, and
clearly demonstrate that they are only diffraction images.
The true pores of these species, when discovered, will, I believe,
be in one central row.
Pleurosigma balticuni. — In a paper recently published in the
Journ. Q.M. 6'., Ser. 2, Vol. XII. p. 155, Mr. T. O'Donohoe has given
an account, accompanied by some excellent photographs, of certain
details of structure of this diatom as seen in a strewn slide
mounted in realgar belonging to Mr. B. J. Capell. By the
courtesy and kindness of Mr. Capell I have also had the privilege
of examining this slide, and am fortunate enough to be able to
320 N. E. BROWN ON THE STRUCTURE OF DIATOMS.
add something concerning the structure to be seen on it that
appears to have escaped the eyes of Mr. O'Donohoe.
In the process of melting the realgar, either the great heat
required, or some chemical action set up by it, has acted upon
some specimens of P. balticum and completely dissolved part
of the shell, leaving only film-like strips flattened upon the
cover-glass, whilst others have been quite unaffected. One
specimen shows in a very clear manner the dissolving action in
progress, but arrested at the moment when a subcentral part
of the diatom had become fused into a structureless strand of
silica, connecting the two ends, which remain intact. These
films above mentioned, which Mr. O'Donohoe has photographed,
will prove, I think, to have an important bearing upon our
more complete understanding of diatom structure.
If the outer surface of a perfect valve of P. balticum be
examined under a binocular, it will be seen that the sides curve
away from the raphe very much as the sides curve away from
the keel of a boat when turned bottom upwards, so that the
surface is nearly always oblique to the surface of the cover-
glass. From this cause I have found the structure of a perfect
specimen extremely difficult to understand, as a very slight
modification of the illumination or alteration of focus under high
powers, or the two combined, produce a number of different
appearances — six or seven have been noticed — all apparently
demonstrating true structure, so that it is practically impossible
to form an opinion as to which view, or views, represent the real
structure of the valve. Owing to this, I suppose, has arisen the
diverse views held of the structure by different authors. 0. Miiller,
for instance, in" the Deutschen Botanischen Gesellschaft for 1898,
Vol. XVI. p. 387, t. 26, fig. 8, regards the pores (by which
I understand he means the black dots) in the cell- wall as
perforations passing completely through the wall, which are
not perfectly tubular, but enlarged at their centre and contracted
to a minute opening on the internal and external surface of the
valve thus :
porej
Mr. T. F. Smith, however, in the Journ. Q. M. C, Ser. 2,
N. E. BROWN ON THE STRUCTURE OF DIATOMS. 321
Vol. III. p. 306, regards the valve as "composed of two layers
of grating"; whilst Mr. E. M. Nelson in the Journ. Q.M.C.,
Ser. 2, Vol. XII. p. 99, fig. 4, states that " in P. balticum
and allied forms the upper membrane has slit-like apertures in
longitudinal rows, while the lower membrane has circular
apertures (fig. 4), where the circular apertures in the lower
membrane are seen through the intercostal silex of the upper
membrane and in a line between the slits." Finally we have
Mr. O'Donohoe's interpretation referred to above.
Until August 1913 I held the view (which I think is the
prevailing one) that the black dots visible on the valve of a
diatom were pores or perforations passing completely through
its substance, and that the white-dot view was an out-of-focus
one. Now, however, the examination of Mr. Capell's slide has
demonstrated to me and to others who have examined it with
me, conclusively and beyond any room for doubt, that many
(possibly all) of the black dots that are ordinarily seen on a-
diatom are not pores at all, or at the most are only pits con-
taining the pore-bearing membrane, and that the white-dot view
is often much more correct for seeing what I believe to be the
true pore-structure than has been supposed.
I have long been puzzled at the behaviour of black dots under
high magnification, and have therefore suspected that they
were not quite what they seemed to be for some time past, but
I think the evidence of Mr. Capell's slide fully explains their
nature.
In any perfect valve of P. balticum it is easy to obtain a view
of a grating-like structure with square meshes, formed of bars-
or rods of silex crossing one another at right angles. In the
partly dissolved films on Mr. Capell's slide this grating is not
evident, but instead the films are seen to consist of parallel
dark rods having a beaded appearance, held in place by a
membrane of silex (see Mr. O'Donohoe's figures, op. cit., t. 14r
figs. 3 and 4). At the ends or other parts the rods are seen
to project in a ragged manner. These rods are those which lie
parallel to the raphe in the perfect grating, while those which
in the perfect diatom form the transverse bars of the grating
structure have been dissolved, leaving no trace, or only a very
faint one, visible. When examined with an oil-immersion objective
at a magnification of 2,000 to 3,000 diameters these bars are
322 N. E. BROWN ON THE STRUCTURE OF DIATOMS.
seen to be thickened in a beaded manner at short equal intervals.
Tn some cases a few of these rods are curved away from the
surface of the valve, and one of them in such manner that part
is seen in surface view and part seen in side view, and traceable
from one view to the other (see Mr. O'Donohoe's photograph,
op. cit., t. 14, fig. 2. where it or a similar rod is shown out of
focus). Now it is obvious that the bead-like swellings occur at
the points where, in the perfect grating, the transverse bars
■crossed and were fused with those parallel to the raphe, and
that these transverse bars were either more easily dissolved or
lie at a slightly lower level than the longitudinal bars, and so
are more quickly attacked by the dissolving action. In all cases
the films are very closely appliel to the cover-glass, indicating
that its cooler surface has in some way retarded the dissolving
process, so that the parts of the diatom farthest from the cover -
glass were always dissolved first. That the longitudinal bars over-
lie the transverse bars seems to be probably the correct view, as
under certain conditions of illumination the longitudinal bars seem
to pass over the transverse ones, and is supported by the testimony
of the curved bar mentioned above as seen in side view. At
a magnification of 3,000 diameters it is clearly seen that the
edge of the bar facing the outside of the diatom is perfectly
even, while the edge facing the interior projects into little hemi-
spheres at the points where (in surface view) it is bead-like (fig. 2).
Also at the marginal part of the valve, where the longitudinal
bars are normally undeveloped and only the transverse bars
are evident, these latter become pressed nearer to the cover-
glass, and are not dissolved.
The bars can be distinctly seen to be solid pieces of silex, which
go to form the strengthening grating and support the membrane
which covers the exterior of the diatom. At a certain focus the
beads or nodes at the crossing of the bars, owin2f to refraction
or diffraction, assume the appearance of black dots so familiar to
all microscopists, demonstrating conclusively that these black
dots are not pores, but shadows produced by some refractive
or diffractive property of the nodes of the grating-bars.
From the movements T have seen diatoms perform it is evident
they must have some means of communication through the valves
with their surroundings, and finding that the black dots on this
diatom are certainly not pores, I sought for them in the membrane
X. E. BROWN OX THE STRUCTURE OF DIATOMS. 323
covering the meshes of the grating. This membrane is extremely-
thin, probably not thicker than the film of a soap-bubble, and
is raised into a slight dome or convexity over each mesh of the
grating. When the apex of these convexities is accurately in
focus, and the headings of the bars seen as black dots forming
squares, the light being central and with a magnification of
2,000 to 3,000 diameters, a very minute dot is seen at the
centre of each square (PI. 2, fig. 1). This central spot I conceive
to be a true pore through the membrane ; it is very minute, at
the most not more than one-third of the diameter of the black
dots themselves, and is probably not more than 1/200, 000th of an
inch in diameter. It is not quite easy to see, but can be made
clearer by the use of a small central stop in the substage con-
denser. I doubt if it can be seen at all at a less magnification
than 1,000 diameters; and with a dry Zeiss y-th, at a magnification
of 3,000 diameters, I do not feel quite sure that I see the pores.
There seems a suggestion of their presence, but I do not think
any dry lens will show them very clearly. Under dark-ground
illumination, with a Leitz dark-ground illuminator, the bars
are white and the headings on them appear much larger than
when seen by direct light, whilst the membrane is not seen at
all, the spaces between the bars being black. But if the funnel-
stop which cuts down the aperture of the lens is removed, the
illumination remaining as before, then the bars appear to be
very slender and black and the membrane whitish, with the
minute pores clear and distinct.
Upon entire specimens of the diatom the pores are difficult to
see, apparently owing to the convex curvature of the shell, but
with a little trouble I have been able to see them in places upon
every specimen examined. Under certain conditions of illumina-
tion a small dark spot, which might easily be mistaken for the
pore, is seen at the centre of each of the beads of the membrane ;
this spot, however, is very much larger than the true pore,
and appears to be some diffraction image, possibly that of the stop
in the condenser, as can easily be demonstrated by moving the
mirror slightly, when the spot is seen to shift its position.
Although all to whom I have shown these pores agree with me
that they are very minute, yet they appear to have a different
size to different observers. To my eye they appear to have about
the proportion to the black dots I have represented in my drawing,
Journ. Q. M. C, Series II.— No. 74. 23
324 N. E. BROWN ON THE STRUCTURE OF DIATOMS. N
to others the}7 evidently seem larger, as one friend said he thought
that about five of them just touching one another would extend
right across one of the meshes of P. balticum, but even at that
rate they would not be more than 1/1 80,000th of an inch in dia-
meter, whilst I think they cannot be more than l/200,000th
of an inch in size.
With regard to Mr. Smith's statement that there is a second
grating, I have not the slightest doubt that the transverse bars
form such a grating, but I have not seen it separately from the
outer grating. In Knowledge for 1911, p. 334, Mr. Smith
reproduces a photograph of P. balticum in which the longi-
tudinal strengthening bars are shown and are there called
" fibrils," a term which Mr. O'Donohoe has also adopted, but
which to me seems wholly inapplicable, as they appear to me to be
supporting structures for the delicate membrane and in no sense
ultimate structures. It may not be out of place here to point
out that the membrane I speak of and illustrate is a totally
different thing from that which Mr. Smith in the Joum. Q. M. 0.f
Ser. 2, vol. 3, p. 301, t. 3, fig. 5, and in Knowledge (1911), pp. 289-
93, and 221-35, and (1912) p. 371 describes and figures as a
"delicate membrane'3 and "torn structure." For it is a
matter of great surprise to me that Mr. Smith did not recognise
that this supposed "delicate membrane " and "torn structure"
has no morphological connection with the diatom. I had sup-
posed, previous to reading his paper, that every one regarded
this appearance merely as an incrustation cementing the diatom
to the cover-glass ; it is of very common occurrence upon
Pleurosigma and some other diatoms. I have always regarded
it as due to the exudation of a residual salt, which, after
boiling in acid, has not been thoroughly washed out of the diatom
(and it is indeed very difficult to wash out completely), so that
when mounting them on a cover-glass the water outside the
diatom evaporates first and the salt then gradually percolates out
through the pores of the diatom, and, in drying, fixes it to the
cover-glass, and being of low refractive index produces the
appearance we so often see.
It will be noted that there is a discrepancy between my
drawings and Mr. O'Donohoe's photographs in the size of the
black dots, for although mine are represented at a greater
magnification, they are smaJler than in the photograph. This is.
X. E. BROWN ON THE STRUCTURE OF DIATOMS. 325
probably because the photographs were taken at a focus where
the membrane is not visible and where diffraction effects are at a
maximum, whilst at the focus of the surface of the membrane
they are reduced to a minimum.
Since writing the above I have had the advantage of being able
to examine a realgar mount of P. balticum belonging to Mr. E.
M. Nelson. The realgar of this slide is not nearly so clear and
brilliant as that of Mr. CapelTs slide, and on some parts of it I
cannot see the pores in the films at all, but there are some films
where they can be most distinctly seen. I mention this, because
others possessing realgar mounts of this diatom might fail to find
the pores on some of the films and believe them not to be present ;
they may be extremely difficult to make out, or quite invisible on
parts of the valve where both longitudinal and transverse grating
or strengthening bars are present.
Pleurosigma angulatum. — Upon Mr. Oapell's realgar slide
are also numerous specimens of this diatom ; some are bent or
contorted, but otherwise, with the exception of two or three
specimens, seem unaffected by the heat or dissolving action.
One of these exceptions, however, is an exceedingly interesting
specimen, and clearly confirms Mr. E. M. Nelson's statement in
the Journ. Q. M. C, Ser. 2, Vol. XII. pp. 98-100, that the valve
of this diatom is composed of two gratings. It is a single valve
and therefore its structure is not obscured by images from the
opposing valve, is fractured in places, and has its outer surface
next the cover-glass, as can be verified by examination under a
binocular. Over a small area some solvent has caused a portion
of the outer grating to peel off, and at one place a small patch of
it is seen adhering to the cover-glass ; this patch is represented at
fig. 5, as seen when magnified 3,000 diameters. At this magnifi-
cation the bars of silex forming the boundaries of the meshes are
seen to cross one another diagonally, forming diamond-shaped
meshes, and are thickened at the nodes or points of intersection
just as in P. balticum, and, as in that diatom, it is these nodes
which produce the black-dot appearance. At the centre of
the membrane covering each mesh a very minute pore can be
seen when the surface of the membrane is accurately in focus.
These pores do not seem to be visible under direct central light
without the interposition of a stop in the condenser, and I find
that they are best seen when illuminated by means of a Leitz
326 N. E. BROWN ON THE STRUCTURE OF DIATOMS.
dark-ground illuminator, but without using a funnel-stop in the
lens. Under this method of illumination they are remarkably
clear and distinct, and the membrane itself appears to be slightly
concave as viewed from the outside of the valve. At one focus
and under slightly oblique illumination, one set of bars appears to
cross over the other set, as I have represented diagrammatically at
fig. 6 ; at this focus the pores are invisible. Upon the specimen
from which the fragment is separated both the outer and inner
gratings are seen to be composed of hexagonal meshes, as at
figs. 7 and 8, and I find it very difficult to get a view of the
diamond-shaped meshes on the entire part of this particular
specimen, although upon other specimens I have been able to see
them and the pores very clearly and easily, as well as the under-
lying hexagonal meshes. It would seem as if the outer grating
may really be a double structure, with a film of diamond-shaped
meshes overlying others that are hexagonal.
Under certain conditions of illumination a third set of bars can
be seen on entire specimens, crossing the diagonals at right angles
to the raphe, but I have failed to see any trace of them on the
separated fragment represented at fig. 5, so that I think it very
probable that they have been dissolved away from that piece,
just as also appears to have been the case in the films of
P. balticum. For I think there can be no doubt that some such
bars exist, because at one focus, under varying conditions of
illumination, the gratings appear to be composed of nearly square
meshes as represented at fig. 9. At a very slight alteration of
focus this appearance alters to the hexagonal one as represented at
figs. 7 and 8, which I take to be that of the exact focal plane of
the membrane covering the meshes of that particular grating.
When the inner grating is examined where the outer grating is
stripped off, looking upon it from the outside of the valve, it first
presents the appearance of a solid plate of white silex with dark
hexagonal perforations in it. At a slightly lower focus this gives
place to hexagonal meshes with dark boundaries and the mesh
covered with a clear membrane having a pore at its centre ; this
latter I look upon as being the true image of the inner grating
and the above-mentioned appearance of a white plate with dark
perforations as an out-of-focus image produced by some refractive
or diffractive property of the membrane, which in some way
produces over each mesh a hexagonal shadow. Below the focus
N. E. BROWN ON THE STRUCTURE OF DIATOMS. 327
of the hexagonal meshes I can sometimes make out a diamond-
shaped arrangement of dark dots as seen in fig. 5.*
In this species, as in P. balticum, wherever a junction of two
or more bars of a grating occurs, there a black dot is seen, due to
diffraction or refraction of the node so formed. And in my
opinion wherever grating structure occurs, the nodes may be
expected to appear as black dots.
At one place a fragment of the valve is broken off and turned
edgeways to the cover-glass. This edge-view shows the two
gratings distinctly, but at the same time, owing to the shadow of
the mass, I am quite unable to see how they are connected to each
other. But from an examination of this piece, as well as of the
valve where the outer grating is stripped off, it is evident that
the faint brown colour peculiar to this diatom resides in the outer
grating, the inner one being colourless.
I cannot, however, confirm Mr. Nelson's statement (Journ.
Q. M. C, Ser. 2, Vol. XII. p. 99) that the meshes of the outer
and inner grating alternate with one another, for in this particu-
lar specimen I think there can be no question that the meshes of
the outer grating are exactly superposed over those of the inner
grating when seen with exactly central light. I have tested them
several times by the unaided eye and by means of a micrometer
in the eye-piece, and always found them to correspond, except
when the light was not absolutely central. Also the edge- view
confirms their superposition so far as I have been able to make it
out, but it is very difficult to get a really good focal image of this
part.
P. angulation has one very obvious peculiarity which I do not
remember to have seen mentioned, namely, that at the ends of the
valve the grating suddenly changes from the hexagonal to the
square type of mesh. This should form a good specific character.
Surirella gemma. — Mixed with Phurosigma balticum on Mr.
Capell's slide are numerous specimens of Surirella gemma, which,
* Mr. T. F. Smith is of opinion that the outer grating is different in
structure from the inner grating, and views of both gratings are given in
The, Microscope and its Revelations, 8th ed. p. 593, pi. 1, figs. 1 and 2. I
am not able to confirm this view, for every structural image seen on the
outer grating I have also"been able to see on the inner grating — it is merely
a question of focus and illumination. The "delicate membrane" on the
outside of the shell described by Mr. Smith I have already noted under
P. balticum, so need not make any further remark upon it.
328 N. E. BROWN ON THE STRUCTURE OF DIATOMS.
in consequence of having seen the minute pores in P. balticum, I
eagerly examined, as I was reminded that some four years ago
whilst examining S. gemma mounted in styrax with a Leitz
-jL.th achromatic oil-immersion objective of 1*3 N.A. I had seen
similar pores or dots on the white beads of that diatom. At the
time, being very busy with other work and thoroughly accepting
the opinion that the black dots usually seen were pores, I paid no
attention to what I then saw. Now, however, I examined them
with fresh interest and found that in this realgar mount the pores
are distinctly visible. To see them, the valve must be resolved
into a grating formed of slender, slightly zigzag black bars, with
the interspaces divided by very slender transverse partitions into
small meshes (the so-called white-dot focus). At a magnification
of from 1,800 to 3,000 diameters on some specimens, but not all, a
minute dark speck or pore at the centre of every one of the
meshes is very clearly visible (figs. 3 and 4) ; at the same time
it is so minute that it requires good eyesight to perceive it,
but, as in other cases, becomes accentuated if a small stop be
placed in the carrier of the condenser. There is therefore no very
great difference in the ultimate structure of this Surirella and of
Pleurosigma balticum, except that in the latter it is the bars
parallel to the longer axis of the diatom which are most evident,
whilst in Surirella gemma the bars transverse to that axis are the
most apparent. It must be understood that I refer here only to
the fine secondary bars or those of the cell-wall, not to the stout
primary bars which form the framework of the diatom and sup-
port the cell- wall. The nodes, formed by the junction of the
slender partitions with the bars, at another focus produce the ap-
pearance of black dots by refraction or diffraction as they do in
Pleurosigma balticum. One specimen of S. gemma on the slide is
crumpled up and the bars bent and turned aside so as to show
their nature very clearly when sufficiently magnified, and demon-
strate that they are exactly of the same character as those of
Pleurosigma balticum — that is, they are the strengthening bars of
the membrane of the diatom. I have been unable to determine
whether there is also a membrane over the inner surface of these
bars, but think it very probable, in which case the white bead-
like appearance will be chambers with minute orifices in their
iuner and outer wall.
This diatom seems to provide the microscopist with a series of
N. E. BROWN ON THE STRUCTURE OF DIATOMS. 329
tests ; with lenses having a smaller aperture than about 0 68 N. A.
only the primary bars of the framework are visible ; with lenses
of a larger aperture, the secondary bars (i.e. those of the cell- wall)
become manifest as very fine lines between the primary bars;
finally with lenses of large aperture and at a magnification of not
less than 1,800 diameters these fine lines or bars are seen to b9
connected by finer transverse bars so as to form a ladder-like
structure, with a minute pore at the centre of each bead-like
space formed by the cross bars, or at another focus the bars can
be resolved into the appearance of rows of dots.
Navicula serians.— The structure of the valve of this species
seems rather difficult to understand. When I first examined it
in search of pores, I found it had a rather coarse grating, with
oblong meshes arranged in six to seven rows on each side of the
raphe, the longer diameter of the meshes being transverse to the
latter. These meshes are closed by a very thin membrane of
silex, at the centre of which can be seen, at a magnification of
3,000 diameters, a minute dark dot, as represented at the upper
part of fig. 10. This clot I take to be a pore. With central
light only a very faint indication of it is seen ; but when a small
central stop is placed in the condenser it becomes clearly visible.
This structure is all that I at first noted. But having re-
examined this diatom with great care under all conditions of
illumination at my command, I have detected structure which had
previously entirely escaped my notica. For I find that if the
outer surface of the valve is illuminated by a Leitz dark-ground
illuminator and examined at a magnification of not less than
2,000 diameters, without reducing the N.A. by using a funnel-
stop, a second grating exterior to and superposed ^upon that
above described can be distinctly seen. This outer grating is
evidently extremely transparent and practically invisible by
central light, so that it very easily escapes notice. I have found
that the easiest way to make it evident is, first to get [the mem-
brane of the coarse meshes in focus, as represented at the upper
part of fig. 10, then gradually but very slightly raise the lens
above that focal plane, until two dark dots appear over each
mesh. If these dots are very accurately focused and the dark-
ground illuminator manipulated so as to illuminate the diatom
with light reflected upon it from the under surface of the cover-
glass, the surface of the valve will be found to have the 'appear-
330 N. E. BROWN ON THE STRUCTURE OF DIATOMS.
ance I have tried to represent at the lower part of fig. 10. I
believe that each of these dots, or minute meshes as they really
are, is closed by an extremely thin membrane of silex, as on one
occasion, when using a dim light reflected from the cover-glass
upon the diatom, the presence of such a membrane seemed to be
very distinctly evident by the light reflected from its surface over
each dark spot and nowhere else. But I entirely failed to see
the slightest trace of a pore in it, although I think it probable
that one exists in each mesh.
Nitzschia scalaris. — When the fine striae on this diatom are
magnified up to 3,000 diameters, they are seen to consist of
small beads or pearl-like dots of silex, which are either black or
white according to illumination. Upon the very thin membrane
between each pair of these rows of beads, a row of very minute
pores is just discernible, as represented at fig. 11, which is
drawn with a camera-lucida, using central light and a green
screen. Under the best of circumstances they are exceedingly
faint, and I am not at all sure that they are accurately spaced
in my drawing, as I found it exceedingly difficult to plot them on
paper by means of a camera-lucida ; but the drawing is suffi-
ciently accurate to show their position. It requires good eyesight
to see them at all, and I do not think they would be visible at a
less magnification than 2,500 diameters. The light must be
most carefully manipulated, and for my vision I have found
them to be most evident in a rather dim light, a glare effaces
them ; also at a very slight touch of the fine adjustment they
instantly vanish. As a test for high powers, manipulative skill
and keenness of vision, I think few things can be found more
suitable than the resolution of the pores of this diatom when
mounted in styrax.
Amphipleura Lindheimeri. — When the surface of this
diatom is accurately in focus (not the black-dot view), a fine
grating with square meshes is seen, which somewhat resembles
that of Surirella gemma ; the bars transverse to the raphe being
straight, whilst those parallel to the raphe form sinuous lines,
because the ends of the short partitions which divide the space
between each pair of transverse bars into square meshes do not
exactly coincide with the ends of the partitions between the
adjoining pairs of transverse bars. At a magnification of 3,000
diameters, when the membrane covering the meshes of the
N. E. BROWN ON THE STRUCTURE OF DIATOMS. 331
grating shows a somewhat bead-like appearance, a very minute
dusky dot, which I take to be a pore, is just discernible in the
centre of every one of them, as represented in fig. 12. These
pores, I think, are smaller even than those of Sarirella gemma,
and are very difficult to see, unless perhaps to younger eyes, as
I judge them to be about the limit of my vision. At a slightly
lower focus the nodes formed by the junctions of the transverse
and longitudinal bars assume the well-known black-dot appear-
ance, and all trace of the other structure disappears. Doubtless
the structure of A. pellucida is similar.
Coscinodiscus heliozoides. — I have nothing to remark
upon the structure of the diatom to which Mr. Siddall recently
gave the above name; but I should like to call the attention of
experts to its remarkable similarity to Stepkanodiscus Hantz-
schianus. I have not been able to compare the two, but feel
sure that C. heliozoides belongs to the genus Stephanodisats,
and have a suspicion that it and S. Ilantzschianus are one
and the same diatom. A good figure of the latter will be found
in the Deutschen Boianischen GesellscJiaft, 1S97, vol. 15, t. 25,
h> 1
Stauroneis phoenicenteron. — When examined at a magni-
fication of a few hundred diameters, the valve of this diatom is
seen to be prettily marked with black dots ; but when magnified
2,000 to 3,000 diameters and very accurately focused, the black
dots are seen to be optical effects produced by the membrane
closing the meshes of the grating. This membrane is slightly
sunk below the general level of the surface of the grating so as
to form shallow pits. When viewed with the light quite central,
without a stop, the bars of the grating appear very much stouter
and the meshes smaller and not so well defined as they do by
other methods of illumination, and I have quite failed to detect
any trace of pores in the membrane by this method. But when
oblique illumination is used, either by means of Powell & Lea-
land's chromatic immersion condenser or by a Leitz dark-ground
illuminator, in such a manner that it is reflected from the under
surface of the cover-glass upon the diatom, then a pore in the
centre of the membrane of each mesh or pit is distinctly per-
ceptible, and the structure has the appearance represented at
fig. 14, which is drawn by means of a camera-lucida from a
portion of the grating adjoining the " stauros," at a magnification
332 N. E. BROWN ON THE STRUCTURE OF DIATOMS.
of 3,000 diameters. The pores are best seen when the light is
not very brilliant.
Triceratium favus. — The structure of this diatom, as well
as that of several other species, has been described and illustrated
in a very interesting article by Floegel in the Journal of the
Royal Microscopical Society, 1884, vol. 4, p. 665, t. 9, figs. 21 and
22, and by Otto Miiller in the Deutschen Botanischen Gesellschaft,
1898, vol. 16, p. 387, t, 26, fig. 5, and 1899, vol. 17, p. 435, t. 29,
figs. 1 to 5. Both these authors figure and describe the valve
as consisting of honeycomb-like hexagonal chambers, which are
open at the outer surface and closed by a very thin perforated
plate at the inner surface of the shell. Floegel made sections of
the valve, and from his drawings of what he saw one would
expect his interpretation to be correct. Miiller's interpretation
is substantially the same. I have not made sections, but from
repeated observations of the external appearance of the valve
I am convinced that their interpretation is not correct. If
the outer surface of the shell of T. favus is examined under a
binocular, with a y^th oil-immersion objective, using either oblique
light or oblique light reflected from the under surface of the
cover-glass upon the object (the Leitz dark-ground illuminator,
when decentred, acts admirably for this purpose), a thin plate of
silex closing the external opening is very distinctly evident, for
light-reflections and shadows can be very clearly seen upon it,
and are seen to move over its surface when the mirror is slightly
moved. The appearance is represented in fig. 15, made from a
camera-lucida drawing, in which the outline was made by viewing
it under a monocular, with central light, at a magnification of
1,500 diameters, and the shading put in to show its appearance
as seen under a binocular at the same magnification with oblique
light, the chamber chosen being midway on the slope between the
apex of the convexity of the outer surface of the valve and the
margin. This closing membrane I believe to be very thin, and
probably any section of it that Floegel made would be nearly or
quite invisible, and therefore easily overlooked. I fail to detect
any pores in it, although I have examined it by several methods
of illumination ; but at the same time there is a faint indication
of some kind of fine-grained surface which may ultimately prove
to be pore-structure.
Upon examining the inner surface of the valve at the same
N. E. BROWN ON THE STRUCTURE OF DIATOMS. 333
magnification and with oblique illumination, the appearance of
the closing plate is as shown at fig. 1G, represented for effect as
at black-dot focus, and drawn and shaded by the same method
as fig. 15. If, however, it is examined by dark-ground illumi-
nation, and especially if the illuminator be decentred so as to
reflect the light from the under surface of the cover-glass upon
the diatom, the closing plates appear to be much more raised
than as seen by oblique light and nearly hemispherical ; which,
however, is the correct appearance I am unable to say. Both
forms of illumination distinctly demonstrate that the outer and
inner closing plates have their central part raised above their
marginal attachment, or, in other words, each closing plate is
separated from its neighbours by a furrow. Floegel and Miiller,
however, both represent the inner plate as perfectly flat and
even, and continuous with that of the adjoining chambers, and in
their drawings (which I think must be somewhat diagrammatic)
of considerable relative thickness. Floegel represents the inner
plate as containing small cavities in its substance, closed on all
sides. Miiller, in the figure he published in 1898, represents the
plate as having small perforations through its substance, whilst
in that published in 1899 he represents the plate as having
small concave pits extending half-way through its substance on
the side facing the interior of the diatom. This latter view is,
I believe, much more correct than the other two interpretations,
for I find that at a magnification of 3,000 diameters, when the
light is oblique, or reflected upon it from the inner surface of the
cover-glass, so that the plate is of a dull greyish-white colour,
it is clearly seen to have pit-like cavities in it closed by a
membrane which is probably situated at the other surface of
the plate. These pits can be clearly demonstrated by gently
moving the mirror, when the shadow formed by the wall of the
pit is seen to move round upon the membrane at the bottom of
the pit. The appearance of the pits as seen with the light
reflected upon them from the under surface of the cover-glass at
a magnification of 3,000 diameters, but enlarged to somewhere
about 10,000 diameters, is as represented at fig. 17. This mem-
brane under this form of illumination is white, and is probably
very thin. When viewed with central light and accurately in
focus, it appears more transparent than the thicker plate-
substance, and the light shows through it more brightly. But
334 N. E. BROWN ON THE STRUCTURE OF DIATOMS.
when examined under dark-ground illumination the reverse
sterns the case, for then the plate-substance appears to have
the transparent of a black sky, and the membrane of the pits
reflects the light so as to appear like minute golden stars. It is
by some refractive or diffractive property of this membrane that
the black-dot appearance is produced, for when the membrane
itself is accurately in focus no black dot is seen ; but if the focal
plane of the lens is above the focus of the membrane, then the
black-dot appearance is produced, and appears to me nothing
more than a deceptive light effect. From the different appear-
ances of this membrane under different methods of illumination
and its contrast with that of the plate, I think it must be of a
somewhat different nature. Although I suspect that it is per-
forated, I have quite failed to perceive any trace of pores in it ;
higher magnification than I am able to obtain is probably needed
for demonstrating anything of that nature.
In conclusion, from the evidence afforded by Mr. Capell's slide
and from the observations I have made upon other diatoms — not
hastily formed opinions, but based upon many hours' examination
under all forms of illumination — it seems clear that we can no
longer regard all the black dots usually seen upon diatoms as
being pores through the shell, although there may be cases
where they are so ; for in the cases examined they are certainly
nothing more than light effects or shadows, either caused by the
nodes of the grating structure, as in Pleurosigma ; or by the
membrane closing the meshes of the grating, as in Stauroneis ;
or by the membrane closing the pits in the cell-wall, as in
Triceratium.
What I take to be the true pores must be sought for in the
thin membrane of silex closing the meshes or pits. If these
are not pores, then I do not know where we are to seek for them.
I think it must be perfectly obvious, to all who like myself have
carefully studied the movements of living diatoms, that there
must be openings or pores through the shell communicating with
the interior. This seems also conclusively proved in cases where
the shell certainly has chambers in its substance, as in Triceratium
favus, Pleurosigma angulatum and others, for in the ordinary
process of mounting the medium penetrates easily into the
interior of the cavities, and they can also be filled by chemical
deposits, which I do not think would be the case if the membranes
N. E. BROWN OX THE STRUCTURE OF DIATOMS. 335
closing these cavities were solid, imperforated films of silex ; no
osmotic theory will account for it.
Also it is quite certain that there is some extrusion of motile
living matter from the interior to the exterior of the diatom,
which is controlUd by the will of the organism.
No one has yet been able to detect any protoplasmic filaments
or pseudopodia (other than the crest of protoplasm along the
raphe) protruding from the pores of diatoms, and if they are as
fine as the pores I have seen would seem to indicate, and as trans-
parent as protoplasm, I doubt if we ever shall see them on the
living diatom, as the nearness of their own refractive index to
that of water would not provide sufficient contrast to enable us
to detect them. Killing and staining do not seem to prove
successful in demonstrating anything of the nature of pseudopodia,
only the crest at the raphe and a very thin layer of protoplasm
sometimes covering the whole shell can be made evident,
so far as I have been able to demonstrate it, but it ought not to
be lost sight of that there is a possibility that a diatom may be
able to speedily retract any protoplasmic matter that it may
protrude from its shell or from the film of protoplasm that some-
times covers its shell, so that at the slightest indication of the pre-
sence of anything injurious, all external protoplasm of the nature
of pseudopodia may be suddenly withdrawn before the diatom is
killed. Usually there is no evidence that any living matter is
protruded to any distinct distance from the shell, except at the
raphe, as any substances taken hold of by a diatom are generally
seen in apparent close contact with the shell, although occasionally
one is seen dragging a niece of dirt along at a short distance
behind it by an invisible thread. But upon a few rare occasions
I have witnessed a diatom seize and move pieces of dirt that were
at an appreciable distance from the shell, and on one occasion
last autumn I was able to measure the interval between the
diatom and the dirt. I was observing a large species of Surirella,
probably S. biseriata, which was moving rather quickly across the
field, when I saw it seize with invisible hands a large piece of dirt
at a little distance from it, and pull it along by its side, without
decreasing the distance between itself and the dirt. I at once put
on an eye-piece with a micrometer scale on it, and carefully noted
the distance separating the dirt and diatom upon the scale, and
then substituted a stage micrometer for the diatom and found that
336 N. E. BROWN ON THE STRUCTURE OF DIATOMS.
the distance to which the pseudopodia (if I may term them so)
extended was between 1/3, 000th and 1/4, 000th of an inch. After
carrying it along across about one-third of the field of view,
it released its hold of the dirt, and in doing so I saw it give a
very slight but distinct jerk, just as if something had snapped
suddenly, for the mass of dirt was very much larger than itself.
This observation was made with a fth lens.
Finally a word as to the pores. It must not be expected that
they can be rendered visible in as easy a manner as Surirella
gemma can be resolved into dots, for they cannot ; they are so
extremely minute that they are by no means easy to detect.
To make them out at all a Tjyth. or xV^n oil-immersion of
1ST. A. 1*3 is necessary, with eye-pieces of sufficient power to bring
the magnification up to at least 1,000 diameters, and often not
less than 2,000 diameters is really required to make the structure
clear, combined with very careful manipulation, a most exact
arrangement of the light and a fair stock of patience. Some can
be seen with central light, but for the most parti have found that
the easiest way to render them visible is by means of a Leitz
dark-ground illuminator, from which, by decentring it, various
modifications of oblique light and light reflected from the under
surface of the cover-glass can be obtained. This method of
reflecting light upon a diatom from the under surface of the
cover-glass may not be generally known, but it can be accom-
plished by decentring the condenser or dark-ground illuminator,
and then raising or lowering it slightly until the right effect is
produced. The process is not a difficult operation, but requires a
little practice, and very often features can be seen much more
clearly by this method than by any other. It is like viewing an
object upon which the sun is shining, with the back to the sun.
When examining a diatom by means of the Leitz illuminator no
funnel-stop must be used in the lens to cut down its aperture.
Sometimes a rather dim light is better than a bright one for
rendering the structure conspicuous.
The lowest power with which I have been able to see the pores
in the films of Pleurosigma balticum is Powell & Lealand's
excellent |-th water-immersion, with which, in combination with
a X 18 eye-piece, they are just perceptible. A Leitz ygth or
yg-th oil-immersion will also demonstrate them and those of
other species, but the lens I have chiefly used has been a Iteichert
N. E. BROWN ON THE STRUCTURE OF DIATOMS. 337
y^th oil-immersion of N.A. 1*3, on account of its greater
magnification, as it is really a xjth, not a true y^th.
Description of Plate 23.
Fig. 1. Part of one of the outer films of the outer grating of
Pleurosigma balticum, x 3,000. The central part from a camera-
lucida drawing, the remainder added to scale from various parts
of the films, to show the manner in which the bars project and
are held in place by the pore-perforated membrane of silex.
Realgar mount, central light, no stop.
Fig. 2. Part of a curved bar from a partly dissolved specimen
of Pleurosigma balticum, which presents both dorsal and edge
views, drawn as seen, to a scale of about 9,000 diameters.
Realgar mount, central light, no stop.
Fig. 3. Part of the grating of Swrirella gemma, x 3,000.
Realgar mount, central light, no stop.
Fig. 4. Four meshes of the same enlarged to the scale of 9,000
diameters.
Fig. 5. Fragment of the film overlaying the outer grating of
Pleurosigma angulatum, X 3,000. Realgar mount, Leitz dark-
ground illuminator, without a funnel-stop at the back of the
objective.
Fig. 6. Diagrammatic enlargement of the bars of the film
over the outer grating of P. angulatum, to show the manner in
which they appear to overlie one another, drawn to a scale
of 6,000 diameters. No pores could be seen when this appear-
ance is visible.
Fig. 7. Outer and inner grating of P. angulatum under the
film of diamond-shaped meshes, x 3,000. Realgar mount.
Fig. 8. Two meshes of the same enlarged to 9,000 diameters.
Fig. 9. Outer grating of P. angulatum, seen at the focus
immediately preceding the hexagonal appearance of fig. 7,
x 3,000. Realgar mount.
Fig. 10. Fragment of the grating of Xavicula serians, x 3,000.
Picric-piperine mount ; upper part showing the coarse inner
grating, as seen with central light and a central stop in the con-
denser, green screen ; lower part showing the outer grating
superposed upon the coarser grating, as seen illuminated by a
Leitz dark-ground illuminator^
338 N. E. BROWN ON THE STRUCTURE OF DIATOMS.
Fig. 1 1 . Fragment of the shell of Xitzschia scalar is, showing
pores, x 3,000. Styrax mount, central light, green screen.
Fig. 12. Fragment of the grating of Amphipleura Lindheimeri,
X 3,000. Styrax mount, central light, green screen.
Fig. 13. Fragment of the shell of a small species of Pinnularia
from the Cherryfielcl deposit, x 3,000, showing what are believed
to be a row of pores down the centre of the outer wall of each
cavity. Picric-piperine mount, central light and green screen ;
can also be seen with dark-ground illumination without a funnel-
stop in the lens and no green screen.
Fig. 14. Fragment of the grating of Stauroneis ])hoenicenteron,
x 3,000. Picric-piperine mount, oblique illumination by Leitz
dark-ground illuminator.
Fig. 15. View of one of the hexagonal cavities of the valve of
Triceratiam favus as seen from the outside of the diatom, showing
the membrane which closes it on the outer side, x 1,500. Styrax
mount ; outline drawn with a camera-lucida as seen under a
monocular, shading added as seen under a binocular with oblique
illumination.
Fig. 16. View of one of the hexagonal cavities of the valve of
Triceratium javus as seen from the interior of the diatom, showing
the raised appearance of the membrane, x 1,500. Styrax mount,
drawn in the same manner as fig. 15.
Fig. 17. Fragment of the membrane shown in fig. 16, drawn as
seen at a magnification of 3,000 diameters, but enlarged to about
10,000 diameters, to show the pit-like nature of the dots upon
the membrane.
Joi'.m. Qucl-ett Microscopical Club. Scr. 2, Vol. XII. No. 74, April 1914.
Jourx. O.M.C.
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N E. Brown, del. ad nat.
Structure of Diatoms.
339
NOTICES OF BOOKS.
Handbook of Photomicrography. By H. Lloyd Hind, B.Sc,
F.I.C., and W. Brough Randies, B.Sc. 8| x 5 j in., xii +
292 pages, 44 plates and 71 text illustrations. London,
1913 : G. Rout ledge & Sons, Ltd. Price 7s. 6d. net.
The student of photomicrography, whether he approach the
subject from the side of photography or microscopy, can hardly
complain of the lack of manuals whose aim is to guide him
in this fascinating subject. The photographer, in reading
Messrs. Hind and Randies' handbook, may perhaps be surprised
that so much space is devoted to details concerning the micro-
scope and its accessories; but he must remember that in order
to photograph an object under the microscope it is very essential
he should possess the necessary knowledge of the instrument
to obtain the best results visually.
Although the subject is treated by the authors in an ele-
mentary manner, at the same time, however, the processes are
discussed in sufficient detail to be of use in research. A special
feature of the book is the very numerous illustrations, and with
each photomicrograph reproduced full details are given of the
process and apparatus used and the method of developing the
negative. This very useful feature enables any special worker
to select the best means for his own branch of the subject,
whether it be the photography of the minute details of diatoms,
the stained sections for use in the histology of plants and
animals, or rock sections and crystals under polarised light.
The subject of colour photomicrography is dealt with in
Chapter XIII. The utility of the Autochrome and Paget plates
for registering the appearance of thin rock sections under
polarised light was excellently demonstrated at a recent meeting
of The Photomicrographic Society.
The subject of cinema-micrography is referred to, but this
could hardly be dealt with fully in an elementary textbook.
In fact, as a means of research it is in its infancy, but fruitful
results may be expected in the future in the study of the
life-history and movements of micro-organisms.
There are useful formulae and tables at the end of the book
and an index. Both authors and publishers may be congratu-
lated on the appearance of the book.
Journ. Q. M. C, Series II.— No. 74. 24
340
PROCEEDINGS
OF THE
QUEKETT MICROSCOPICAL CLUB.
At the 492nd ordinary meeting of the Club, held on October 28th,
1913, the President, Prof. A. Dendy, D.Sc, F.R.S., in the chair,
the minutes of the meeting held on June 24th, 1913, were read
and confirmed.
Mr. S. G. H. Knox was balloted for and duly elected a member
of the Club.
The Hon. Secretary said they were favoured with the presence
of several visitors, to whom he offered a hearty welcome on behalf
of the Club.
The President said that members would be sorry to hear that
since the last ordinary meeting the Club has sustained the loss of
one of our more well-known members : the Right Hon. Sir Ford
North, F.R.S., died on October 12th, at the age of eighty-three.
He was a Fellow of the Royal Society, and a keen entomologist.
He was elected a member of the Club in 1894, became a member
of the committee in 1899, and was one of the vice-presidents from
February 1901. His patience and experience in directing a
meeting when he occupied the chair made him a most valuable
member of the Club, and one whose loss will be much regretted.
Mr. E. J. Spitta said that Sir Ford North hardly ever missed
attending the meetings of the Club, and he thought that a more
charming man never existed. Often in committee he would
remain silent for a long time, and would then rap out a very
clever opinion on the matter before them. During the four years
of his (Mr. Spitta's) presidency he had frequent opportunities of
intercourse with Sir Ford North, and on every occasion had found
him a courteous friend.
Mr. Spitta then moved: "That the Committee be empowered
through the Secretary to convey to the relatives of the late Sir
Ford North an expression of their regret and sympathy."
This having been put to the meeting, it was unanimously
carried by the members present silently rising.
PROCEEDINGS OF THE QUEKETT MICROSCOPICAL CLUB. 341
The list of donations to the Club was read, and the thanks of
the members were voted to the donors.
Mr. S. C. Akehurst (Hon. librarian) read a note on "A
Changer for Use with Sub-stage Condensers." The method of
using the changer was demonstrated to the members.
Mr. S. C. Akehurst also read a note on " A Trap for Free-
swimming Organisms." Two forms of the little piece of apparatus
were exhibited, and details demonstrated by drawings on the
blackboard.
The President said he had examined the extremely ingenious
contrivance for quickly changing the condenser. It was a matter
which very strongly appealed to him, as he had often much
trouble in changing condensers.
Mr. D. J. Scourfield, referring to the trap for free-swimming
organisms, said this method opened new possibilities wThen
dealing with extremely minute organisms. One can get to a
certain point with the centrifuge ; but it is sometimes desired to
go a little further in concentrating. He thought it a very
ingenious piece of apparatus.
A paper on " The Gastrotricha," communicated by Mr. James
Murray, F.R.S.E., was introduced by Mr. Scourfield, who said
that it was just twenty-four years since the subject had pre-
viously been brought before the notice of the Club. This was
a paper read by T. Spencer on September 27, 1889, on a new
species he provisionally named Polyarthra fasiforniis. This is
now Stylochaeta fusiformis. Mi1. Murray said that he had
been reluctant to attempt an introduction to the study of the
Gastrotricha, as his knowledge of the group was by no means
profound, and had been only recently acquired. The main part
of the paper is an annotated bibliography which it was hoped
would save students much of the trouble the author had ex-
perienced. If the bibliography be too condensed, the student is
always liable to suspect that a work omitted from it has not
come to the knowledge of the compiler. Here, however, all
important general, biological and systematic works known to
the author are included, as well as any really important
faunistic studies. Every work is given in which new, or sup-
posed new, species or groups of higher value are described. It
is unfortunate that the Gastrotricha — which include those old
familiar friends of the students of pond-life, Chaetonotus lanes
342 PROCEEDINGS OF THE
and Ichthydium podura — have no popular name. Gosse pro-
posed the name of " hairy-backed animalcules." This is entirely
unsuitable, since some of the genera are not hairy-backed
(Ichthydium, Lepidoderma). Mr. Murray was not able to suggest
an appropriate name. The name suggested by the scientific
term for the whole group, which embodies almost the only
character which they all possess, is unsuitable for popular use.
The Gastrotricha are not animals which can be named offhand.
The days when we found Chaetonotus lanes and Ichthydium
podura, occasionally varied by C. maximus, on all our pond-life
excursions are over. There is a host of species which have
contributed to the records of C. larus. These species are all
alike to a casual glance, but are distinguished by minute
characters — the possession of small branches by certain of the
bristles, the form of the minute scales which bear the bristles,
etc. Some of these are so delicate that an oil-immersion lens
would be needed for their certain determination. The author
expressed his thanks to Messrs. Rousselet, Bryce and Starring
for assistance given in the preparation of this paper. The paper
then goes on to describe the form and structure of the Gastro-
tricha, their haunts and habits, an historical sketch of the
genera, their classification, a key to the genera and a list of
the eighty-three species which have been described, notes on the
identification of species and on some species Mr. Murray had seen,
and concludes with a bibliography of seventy-two items. Mr.
Scourfield illustrated his remarks and comments by references to
a number of sketches he had drawn on the blackboard.
The President had much appreciated Mr. Scourfield's resume
of Mr. Murray's paper. He referred to the " fish-hook " spines
and other extraordinary specific characters, which, he thought,
could not possibly be explained as due to natural selection. The
Club was very much to be congratulated on having such an
important paper contributed to the Journal.
Mr. llousselet said these organisms could be preserved quite
well in 5-per-cent. formalin. He remembered Mr. Spencer's
paper in 1889 quite well, and had differed from him at the
time, and had said fusiformis was not a rotifer, but could
not then say what it was. The animal was taken at a Club
excursion.
On the motion of the President a cordial vote of thanks was
QUEKETT MICROSCOPICAL CLUB. 343
passed to Mr. Murray for his paper and to Mr. Scourfield for
giving them so good a resume of it.
Mr. James Grundy described and exhibited "An Improved
Form of Cheshire's Apertometer."
Mr. Grundy said that of the value of Mr. Cheshire's form of
apertometer there can be no doubt. The aim of Mr. Nelson has
been to enable the N.A. values of an objective to be read on the
apertometer easily and accurately. Distinctness and clearness of
reading have been effected by increasing the number of marked
values of N.A. from 9 to 22 without the confusion that over-
crowding of the lines would entail. To accomplish this, short
arcs of circles are used instead of whole circles. A valuable pro-
perty of these is the clear visibility of the ends or edges of the
arcs : they are seen more distinctly than complete circles would
be. The contrast between the white ground and the short black
lines favours this. The exterior edges of the arcs denote the N.A.,
and thus give most convenient, accurate, and definite positions for
reading.
Mr. F. J. Cheshire said it might interest members to know
that he described his apertometer before the Club some ten years
ago. When Zeiss first issued Abbe's form, it was marked to read
only to 005. In a paper defending this marking, read before the
R.M.S. in 1880, Abbe dealt with the accuracy it was necessary
to strive for. On the Zeiss apertometer it is possible to read to
| per cent. ; but blue rays alone will give a difference of 1 per
cent, over a reading taken with red light, so that the maximum
accuracy it was advisable to attempt to obtain was 1 per cent.
Mr. Cheshire thought that one point in Mr. Nelson's diagram
largely vitiates the advantages given by a greater number of
fiducial Hues — that is, that the fiducial edge in the diagram is
the outer edge of the line ; and, again, the lines are of varying
thickness. There are twenty-two edges of lines on the diagram
with no fiducial value. He himself thought that his original
form was not capable of further accuracy. Mr. Cheshire then
described, and subsequently demonstrated, another method of
measuring N.A., which he considered an improvement on the
older form.
A visitor — Mr. M. A. Ainslie, K.N. — said that experience in
the use of both the original form of Cheshire's apertometer and
the modification thereof recently suggested by Mr. Nelson has
344 PROCEEDINGS OF THE
revealed one or two difficulties in connection with the reading of
the instrument — that is, if any accuracy in the second decimal
place is required. The first difficulty is due to the fact that in
Mr. Cheshire's instrument we have to interpolate or estimate
between two divisions on a scale, one of which is not visible, being
outside (apparently) the margin of the back lens of the objective.
This renders the estimation of the second place of decimals in the
N.A. uncertain,' and although Mr. Nelson's modification of the
original instrument is somewhat better in this respect, yet the
very means adopted to improve the reading — namely, the intro-
duction of a large number of additional circles — is likely to con-
fuse the diagram and bewilder the observer. In either the old
form or the new of Cheshire's instrument, a count has to be made
of concentric circles — a thing which, simple as it may seem, is
peculiarly liable to confuse the eye, so that it is only after count-
ing several times that one feels certain that the number is, say,
eight, and not seven.
Mr. Ainslie exhibited and described a new method of reading
the N.A. of an objective,
The President said the Club was much indebted to Mr. Ainslie
for his communication, and also to Mr. Cheshire and Mr. Grundy,
to whom the thanks of the meeting were unanimously voted.
At the 493rd ordinary meeting of the Club, held on Novem-
ber 25th, 1913, the President, Prof. A. Dendy, D.Sc., F.R.S.,
in the chair, the minutes of the meeting held on October 28th,
1913, were read and confirmed.
Messrs. W. M. Bale, B. Shepherd, H. Dobell, E. W. Ramsay,
M. R. Licldon, A. Panichelli, Robert Young, W. G. Tilling, and
E. J. E. Creese were balloted for and duly elected members of
the Club.
The President read a letter from the nephew of the late Sir
Ford North, which was in reply to the vote of sympathy passed
at the last meeting.
Mr. C. E. Heath, F.R.M.S., brought before the notice of the
meeting a device for preventing damage to objective or slide,
especially when the higher powers are used, in cases where the
microscope is liable to unskilful usage, as, e.g., at soirees. A
small piece of thin metal — steel was suggested — is taken, having
QUEKETT MICROSCOPICAL CLUB. 345
a hole in it of such a size as to permit of the screw-end of an
objective passing through it up to its flange. In use the plate is
placed over the end of the nose-piece, and the objective screwed
home through it. To a projecting portion of the metal plate is
fitted a short length of brass tube or rod — say | in. diameter,
which has been tapped internally, the direction of the tube being
parallel to the optic axis, and just clear of the objective. A fine
screw (25 threads to an inch) is fitted to the tube, and at the
lower end is provided with a milled head. The microscope is
focused in the usual way, and the screw then screwed down until
it is in contact with the stage clear of the cover-glass, and so
prevents any movement of the body, and possible damage. If
required, a small amount of slack may be left for possible focusing
by visitors who can use a microscope.
The President described " A Red- Water Phenomenon due to
Euglena." He had noticed a curious appearance in a pond near
Manchester : the water was of a brilliant red colour. This, on
examination, proved to be due to Euglena, which formed quite a
thick scum of the red colour. The colour was confined to the
surface, and had a dry, powdery appearance that was very notice-
able. Microscopic examination showed the Euglena to be of a
large species, and the red coloration to be due to the replace-
ment of the chlorophyll by haematochrome. The main mass of
the body was coloured. Those floating on the surface were in a
resting condition ; but, at the bottom, all were actively swimming
about. There was apparently no intermediate stage, and at once
the question arose : How did the organisms get from the bottom
to the top of the pond % It was found that the Euglenae at the
bottom of the pond secreted large quantities of mucilage. The
organism, in the presence of sunlight, gave off bubbles of oxygen,
which became entangled in the mass of mucilage, and presently
carried the mass to the surface, trailing Euglenae after it, so that
they were collected at, and formed a scum on, the surface. The
colour of the scum changed during the day, from red in the
morning to green in the afternoon, the actual change from one to
the other being accomplished in about half an hour. Cunning-
ham had observed similar changes in Euglena viridis, near
Calcutta, lie records the scum as bright red in the morning
dull red at midday, and green in the evening, and by sunset an
intensely vivid green. The reverse took place just about dawn,
346 PROCEEDINGS OF THE
so that at sunrise the pond scum was brilliant red again. The
President asked if any members had seen a similar appearance.
Mr. C. F. Rousselet, when in South Africa with the British
Association in 1905, had noted near the Matoppo hills a similar
red Euglena, which he had not before seen.
The Hon. Sec. paid considerable attention to the " Breaking of
the Meres," but had never seen red Euglena. He had observed
red scum, due to other causes. The phenomenon noticed by the
President was, however, not unique in this country. Some years
ago he had received some " red scum " material from Norfolk,
which was definitely identified as Euglena. The organisms were
crowded in their middle region with starch grains, and starch in
such a form that it was not affected by iodine.
Mr. A. E. Hilton asked whether the red colour indicated the
decay of the chlorophyll formed during the previous day.
The President did not think that the change from green to red
indicated any process of decay — this change of colour was not
unique in Nature, as the snow plant could be obtained both red
and green, and apparently the change was due to nitrogen starva-
tion. He found this to be the probable cause when he had two
jars side by side, one red and the other green, and a fly had
fallen into one jar and had decayed ; the slightest trace of nitro-
genous food was sufficient to cause the change, which he thought
could not be regarded as a product of decomposition. Dr.
Cunningham thought that both kinds of pigment were present at
the same time, but that they were differently placed when the
change of colour was observed ; but whether this was the sole
reason for the change in the Euglenae was not certain.
Mr. James Burton (Hon. Secretary) read a short paper,
" On the Disc-like Termination of the Flagellum in certain
Euglenae."
Mr. James Burton also read a note on " A Method of Marking
a Given Object on a Mounted Slide."
Mr. M. Blood said he usually put a spot of ink on the bright
spot of light formed on the slide by a high-power condenser, and
when it was dry, scraped the centre away.
Mr. Spitta, after finding and centring the object in the field,
replaced the objective with a dummy of similar size, on to the lower
end of which had been fastened a rubber letter 0, such as is to be
obtained in small movable-type printing outfits. The letter is.
QUEKETT MICROSCOPICAL CLUB. 347
inked, and gently lowered on to the slide. He had found this
method quite satisfactory.
Mr. James Grundy read a paper communicated by Mr. E. M.
Nelson on " The Measurement of the Initial Magnifying Powers
of Objectives." Mr. Grundy added a few notes in amplification
and explanation of some points in Mr. Nelson's paper, which he
illustrated with blackboard diagrams.
A vote of thanks to Mr. Grundy was carried unanimously.
At the 494th ordinary meeting of the Club, held on December
23rd, 1913, Mr. D. J. Scourfield, F.Z.S., F.R.M.S., Vice-
President, in the chair, the minutes of the meeting held on
November 25th, 1913, were read and confirmed.
Messrs. M. A. Ainslie, R. A. Saunders, T. B. Lock, F. S.
Mumford, A. Green, H. F. W. Sprenger, W. D. Deed and J. H.
North were balloted for and duly elected members of the Club.
A letter was read from the Poyal Microscopical Society
enclosing a copy of a resolution passed by their Council, thanking
the members of the Q.M.C. who exhibited at their Conversazione
on November 19th.
Mr. B. M. Draper read a paper on a new live box for the
exhibition of flies and other large objects under low powers of the
microscope — the article itself being exhibited in the room under a
Greenhough binocular.
Mr. B. M. Draper also read a paper describing a new stop for
obtaining dark-ground illumination with the Greenhough
binocular — the subject being illustrated by the exhibition of the
stop and by a diagram upon the blackboard.
The Chairman thought the live box well adapted for showing
large objects, and inquired if any means were adopted for con-
fining the insects or controlling their movements whilst under
observation.
Mr. Draper said there was no other means of controlling the
movement of the objects except by the use of a small cell, but
the power used being a low one, the whole cell was generally in
the field at the same time ; and in answer to a question by
Mr. Rousselet, he said that the cover of the cell was only held
down by its own weight, but it was prevented from slipping
sideways by the upright pins mentioned in the paper.
q
48 PROCEEDINGS OF THE
The thanks of the meeting were voted to Mr. Draper for his
papers.
Mr. W. R. Traviss exhibited under microscopes two fragments
of quartz crystals. Referring to one of the mounts, he said it
showed a series of seven faint lines across the field, parallel, but
not equally spaced. He suggested that the lines at one time
were respectively the outer surfaces of the crystal. The plane
of this particular surface in the mount referred to was at right
angles to the plane of the microscope stage, so that by focusing
down one could look along this plane. It was then noted that
this " old crystal surface " was covered with a number of very
small crystals, or debris, which had been deposited on this plane.
Presently the crystal went on growing, and again a period of rest
and more debris deposited or formed. This was repeated seven
times, but the exterior face was quite smooth.
Then as to the occasional presence of contained bubbles of
liquid in quartz (and other) crystals. It was suggested that it
was possible that they were formed by a bubble of gas adhering
to perhaps the under surface of a growing crystal, and material
being deposited round and over it.
Some discussion followed on liquid enclosures in crystals and
the nature and method of identification of the gases contained.
The chairman drew attention to a paper by Mr. Ashe on the
effects of temperature on enclosed liquids. (Journ. Q. M. C, Ser.
2, Vol. VIII., pp. 545-8, pi. 28.)
Mr. E. M. Nelson sent a note on a peculiar form of diatom.
During an examination with dark-ground illumination of Mr.
Siddall's filaments on some Coscinodisci in a diatom gathering,
mounted and kindly given me by Mr. Chaffey, a small portion
of sandy grit was found to have similar filaments protruding from
it. Its colour was a golden yellow, the same as the sandy grit
usually seen in this kind of slide, which contains diatoms mounted
in sea-water in their natural state. The dark-ground illumi-
nator was removed, and when the object was examined by an
oil-immersion gth with transmitted light from an achromatic
condenser, the green chlorophyll pustules of a diatom could just
be made out inside the conglomerated mass of sandy grit. A
search was then made over the slide, and three or four other
similar specimens were found. So it appears, then, that there is
a " caddis-worm " form of a diatom. What species this diatom
QUEKETT MICROSCOPICAL CLUB. 349
may be no one can say, for it cannot be seen with sufficient dis-
tinctness for identification. Probably in its cleaned state it may
be a very common and well-known form, but had it not been for
its filaments, its presence in these sandy conglomerations would
never have been suspected. Other species of diatoms on this slide
were quite free from sandy grit.
Mr. Nelson ako sent a note on Amphipleura Lindheimeri.
At the 495th ordinary meeting of the Club, held on January
27th, the President, Prof. A. Dendy, D.Sc, F.R.S., in the
chair, the minutes of the meeting held on December 23rd, 1913,
were read and confirmed.
Messrs. H. A. Gee, G. H. Shelley, A. Walker, the Rev. G. H.
Nail, Lieut.-Col. J. Clibborn and L. E. Harris were balloted for
and duly elected members of the Club.
The list of nominations by the Committee of officers for the
ensuing year was then made — there being no change from that
elected last year.
The President having mentioned that four members of the
Committee — Messrs. Wilson, Heron- Allen, Bryce and Caffyn —
would retire by rotation, but were eligible for re-election, except
Mr. Caffyn, who did not wish to serve again, asked for nomina-
tions of members to fill the vacancies created.
The following gentlemen were thereupon nominated : Messrs.
Heron -Allen, Wilson, Bryce, Gabb, A. Morley Jones and Todd,
whose names would appear on the voting paper at the next
ordinary meeting.
Mr. A. E. Hilton was then elected as Auditor on behalf of the
members.
Mr. S. C. Akehurst (Hon. Librarian) read " Some Remarks on
Sub-stage Illumination " ; the subject was illustrated by a number
of photographs projected upon the screen.
Mr. T. A. O'Donohoe read a paper, entitled "An Attempt to
resolve Pinnularia nobilis" This was illustrated by photographs
projected upon the screen.
Mr. M. A. Ainslie said that the whole question of diffraction
spectra was of course of vital importance in the resolution of any
fine structure, and in many cases it could not be done with a dry
lens. By means of diagrams drawn on the blackboard as he pro-
350 PROCEEDINGS OF THE
ceeded, the speaker showed the effects of diffraction spectra under
varied conditions. In using annular illumination they were
using a number of central cones of illumination overlapping to
form the annular. He also pointed out the danger of using
annular illumination unless great care was exercised as to the
tube length.
Mr. Blood said it was extremely easy to resolve diatoms with a
central stop — in which case they were merely seeing the image of
the stop. In many objectives the central portion and the
extreme edge were over corrected, but the intermediate zone was
quite right.
Mr. Brown said he had been examining Pinnularia nobilis for
the last forty years, and thought he had obtained a resolution of
it, but not the same as that described by Mr. O'Donohoe. For a
long time he was unable to get any resolution, but he believed he
had now done so, and hoped shortly to read a paper on the subject.
Mr. Akehurst explained that the photographs shown in illus-
tration of his paper were taken to show the contrast between the
ordinary and the new method of illumination with central stop
below the condenser, but without cutting down the N.A. of the
objective.
Votes of thanks were cordially passed to Mr. Akehurst and
Mr. O'Donohoe for their papers.
In place of the usual monthly conversational meeting, a Conver-
sazione was held on February 10th, in the Great Hall, King's
College, by kind permission of the Principal. Nearly five hundred
members and visitors were present, and about 170 microscopes,
besides other apparatus, were on exhibition. It is not possible to
give a complete list of the objects shown ; but among others may
be mentioned a number of coloured drawings of water-mites,
including a series of fifteen figures illustrating the life-history of
Hydrachna ylobosa (de Geer), by C. D. Soar ; foraminifera under
microscopes, and material from the sea-bottom in various stages
of preparation, by Messrs. Heron-Allen and Earland ; living-
rotifers by Messrs. Bryce, Dunstall, Rousselet, Scourfield and
others ; stereophoto-micrographs by Messrs. A, E. Smith and
Taverner ; photomicrographic apparatus and some sixty natural-
colour lantern-slides by E. Cuzner ; some fine photomicrographs
in colour of polarised rock sections by Messrs. Cafiyn and Ogilvy.
QUEKETT MICROSCOPICAL CLUB. 351
Mr. H. F. Angus (H. F. Angus & Co.) showed the Reichert
demonstration and comparison eye-piece for comparing the fields
from two microscopes in one eye-piece, in which the field is divided
laterally, Akehurst's phototropic pond-life trap, Draper's all-glass
live box, the Finlayson revolving disc for the exhibition of a
series of opaque objects, Heath's objective-guard, etc.
Mr. Lees dirties (C. Baker) had on view several Greenhough
binocular microscopes, multicolour illumination of crystals, and
three forms of the Cheshire apertometer.
Mr. C. Beck (R. & J. Beck) exhibited the new model high-
power binocular, employing a -jVth oil-immersion objective, with
a very simple and efficient adjustment for inter-pupillary
distance.
Mr. J. W. Ogilvy (E. Leitz) showed several new short-tube
high-power binoculars employing a TVth oil-immersion objective ;
a comparison eye-piece for comparing simultaneously complete
fields of two microscopes; and several examples of the Green-
hough binocular — one especially adapted for metallurgical work.
Mr. F. W. W. Baker (W. Watson & Sons) exhibited a new
model Yan Heurck, with 2| in. movement to the stage, and
complete rotation, also a new workshop metallurgical microscope
and some twenty microscopes with various objects, including a
series of seven illustrating the development of the chick from
twenty-four hours to four clays.
During the evening a lantern lecture was given in the large
theatre by Mr. F. W. Watson Baker (Watson & Sons) on " Some
Microscopical Hows," and subsequently Mr. C. Lees dirties
(C. Baker) gave a lantern demonstration, in the same place, of
natural-colour photographs and photomicrographs of miscellaneous
and microscopic objects prepared by the Paget process. Both
lectures were well attended and much appreciated.
Of late years the club has not held conversaziones, and during
the evening the wish was several times expressed that such
gatherings should be more frequent, and certainly that no long
interval should elapse between this and the next. (The last
conversazione was held nearly seventeen years ago — on May 4th,
1897 — in the smaller Queen's Hall.)
352
PROCEEDINGS OF THE
At the 496th ordinary meeting of the Club held on February
24th, which was also the forty-eighth annual general meeting,
the President, Prof. A. Dendy, D.Sc, F.R.S., in the chair the
minutes of the meeting held on January 27th were read and
confirmed.
Messrs. A. 0. Gooding and Raymond Finlayson were balloted
for and duly elected members of the Club.
The list of donations to the Club were read, and the thanks of
the members voted to the donors.
Mr. N. E. Brown and Mr. F. W. Watson Baker having been
appointed scrutineers, the ballot for the election of officers and
Council for the ensuing year was proceeded with ; it being sub-
sequently announced that the following gentlemen had been
elected as
President
• • •
Four
Vice-Presidents
Treasurer
Secretary
Assistant Secretary
Foreign Secretary .
Reporter ....
Librarian . . .
Curator ....
Editor ....
Four Members of
Committee.
Prof. Arthur Dendy, D.Sc, F.R.S.
C. F. Rousselet, F.R.M.S.
E. J. Spitta, L.R.C.P., M.R.C.S., F.R.A.S
D. J. Scourfield, F.Z.S., F.R.M.S.
IProf. E. A. Minchin, M.A., Ph.D., F.R.S.
Frederick J. Perks.
James Burton.
J. H. Pledge, F.R.M.S.
C. F. Rousselet, F.R.M.S.
R. T. Lewis, F.R.M.S.
S. C. Akehurst, F.R.M.S.
C. J. Sidwell, F.R.M.S.
A. W. Sheppard, F.Z.S., F.R.M.S.
(A. Morley Jones.
E. Heron-Allen, F.L.S., F.Z.S., F.R.M.S.
J. Wilson, F.R.M.S.
D. Bryce.
The Hon. Secretary read the Committee's forty-eighth annual
report. Fifty-five new members were elected during the past
year, and the total number is now 441.
The Hon. Curator reported that 2,000 slides had been borrowed
by members, and that 192 preparations had been added to the
collection during the past twelve months.
The Hon, Treasurer presented the Annual Statement of
QUEKETT MICROSCOPICAL CLUB. 353
Accounts and the Balance Sheet for 1913, which had been duly
audited and found correct.
The adoption of the Committee's report and the Balance Sheet
was moved by Mr. A. M or ley Jones and seconded by Mr.
Morland and carried unanimously.
Mr. D. J. Scourfield, F.Z.S., F.R.M.S., Vice-President, having
taken the chair, the annual address was delivered by the President,
who took as his subject " Organisms and Origins."
The usual votes of thanks to the President for his address, and
to the officers of the Club for their services during the past year,
were carried by the meeting. A special vote of thanks was
passed to the Hon. Secretary and to Mr. J. Grundy for their
services in so successfully organising the recent conversazione.
354
FORTY-EIGHTH ANNUAL REPORT.
Your Committee are glad to be able to assure the Club of its
continued prosperity. During the year ending December 31st,
1913, fifty-five new members were elected ; this number has been
equalled only once, and exceeded only once — when there were
fifty-seven elected— during the recent years of which any record
has been found. Eleven have resigned, and four were lost by
death, leaving the present number 441. Among those lost by
death should be mentioned the Eight Hon. Sir Ford North, for
some years a Vice-President and a valued member of the Club.
An obituary notice appeared in the November number of the
Journal.
Both the Ordinary and Gossip Meetings have been well attended,
in fact on several occasions the number present was somewhat
more than the capacity of the room would accommodate with
a due regard to comfort.
The papers and notes read and exhibits contributed during the
year were as follows :
Jan. W. M. Bale, F.B.M.S., of Victoria, Australia. Notes
on some of the Discoid Diatoms. Communicated by
the President.
H. Whitehead, B.Sc. British Freshwater Bhabdo-
coelida (Planarians). Communicated by J. Wilson.
C. F. Bousselet, F.B.M.S. The Botifera of Devil's
Lake : Description of a New Brachionus.
E. M. Nelson, F.B.M.S. Note on Pleurosigma angu-
latum ; Note on a Coloured Coma observed in
examining A. Ralfsii.
Feb. Prof. A. Dendy, D.Sc, F.B.S. By-products of Organic
Evolution. Presidential Address.
March. E. Heron-Allen, F.Z.S., F.L.S., and A. Earland,
F.B.M.S. On some Foraminifera from the Southern
Area of the North Sea, dredged by the Fisheries
cruiser Huxley.
n D. Bryce. Five New Species of Bdelloid Botifers.
j?
>>
55
FORTY-EIGHTH ANNUAL RETORT. 355
April 0. D. Soar, F.L.S., F.R.M.S. Two New Species of
Water-mites.
,, G. T. Harris. The Collection and Preservation of the
Hydroida.
May. T. A. O'Donohoe The Minute Structure of Coscino-
discics asteromphalus and of two Species of Pleuro-
sigraa.
June. H. Sidebottoin. The Lagenae of the South-West
Pacific.
E. M. Nelson, F.R.M.S. On a New Method of Mea-
suring the Magnifying Power of an Objective.
Oct. James Murray, F.R.S.E. The Gastrotricha.
,, E. M. Nelson, F.R.M.S. Note on an Improved Form of
Apertometer.
Nov. James Burton. On the Disc- like Termination of the
Flagellum in some Euglenae.
James Burton. On a Method of Marking a Given
Object on a Mounted Slide for Future Reference.
E. M. Nelson, F.R.MS, On the Measurement of the
Initial Magnification of Objectives.
Dec. B. M. Draper. On Dark-ground Illumination with the
Greenhousdi Binocular.
>)
n
D
At the Ordinary Meetings the following slides and apparatus
were exhibited :
Jan. W. Watson Baker. New Model Microscope, having a
Side screw Fine Adjustment, and New Objective
Changer, etc.
„ A. A. C. Eliot Merlin, F.R.M.S. Photomicrographs of
Coscinodiscus heliozoides, showing Pseudopodia.
March. A. A. C. Eliot Merlin, F.R.M.S. Five Photomicro-
graphs taken at x 320 of various Diatoms.
April. Presented by G. T. Harris. Mounted Hydrozoa, ex-
hibited under Microscopes by Messrs. H. F. Angus
&Co.
May. J. Watson, a visitor. A Slide showing Multiple Images
formed by the Cornea of the Eye of a Bee.
E. Pitt. Various Microtomes exhibited and explained,
3>
with Demonstration of Ribbon Section-cutting
»■
Journ. Q. M. C, Series II.— No. 74. 25
»)
"
o56 FORTY-EIGHTH ANNUAL REPORT.
June. A. A. 0. Eliot Merlin, F.R.M.S. Photomicrograph of
Foot of Ceylon Spider.
E. M. Nelson, F.R.M.S. A Slide of Green Trap show-
ing Structure resembling Vegetable Tissue.
,, W. Traviss. Apparatus for Use in Pond Hunting,
enabling a Sample of Water to be obtained at any
desired Depth.
,, James Grundy. Apparatus for use in connection with
E. M. Nelson's paper " On a Method of Measuring
the Magnifying Power of an Objective."
Oct. S. C. Akehurst. A Changer for Sub-stage Condensers.
S. C. Akehurst. Trap for Minute Free-swimming
Organisms.
Messrs. Grundy, Cheshire and Ainslie. Various Aper-
tometers.
Nov. C. E. Heath, F.R.M.S. Objective Guard for Preventing
Damage to High-power Objectives.
Dec. B. M. Draper. A New Form of Transparent " Live
Box " for the Exhibition of Living Organisms, chiefly
Insects. Also a Special Form of Stop for Dark-
grouncl Illumination with a Greenhough Binocular.
„ W. Traviss. Specimens of Quartz showing under the
Microscope a Laminated Structure.
Your Committee feel that the Club is greatly to be congratu-
lated on the inclusion in its Journal of such valuable papers.
Not only is their publication in our Proceedings an honour to the
Club, but the actual value of the communications as a contribu-
tion to science, and especially to that always difficult and often
little-appreciated subject, classification, makes the Journal a
standard work of reference. The Club has also been the means
of making known and recording a number of new species among
the Rotifera, the Entomostraca, and Water-mites, by members
who are authorities in these several classes. While thanking
those members who have contributed to the success of the Club,
the Committee would take this opportunity of urging upon
others the great advantage of bringing before the Club subjects of
interest in the form of short papers or notes, and the profit they
would themselves obtain by putting their knowledge into the
concrete and definite shape required for this purpose. The
FORTY-EIGHTH ANNUAL REPORT. 357
Committee at the same time wish it to be remembered that one
of the foremost aims of the Club is to assist the amateur and the
beginner, both by providing papers of a somewhat elementary
character, and by assuring them that, particular]}' at the Gossip
Meetings, they will find friends willing and anxious to assist them
in their efforts in gaining experience in the best methods of using
their instruments, and in the task of identifying specimens.
The Librarian reports that there has been a fair demand for
books during the year, but somewhat less than that for 1912.
The card index and the numbering and rearrangement of the
books are nearly completed, and the path cleared for commencing
the final details of the new edition of the Catalogue. The
thanks of the Club are due to Messrs. Caffyn, Todd and L. C.
Bennett for the great amount of assistance they have given the
Librarian in these matters.
During the year under review the following volumes have
been added :
LIST OF BOOKS PURCHASED SINCE JANUARY 1913.
British Parasitic Copepoda. T. & A. Scott. Vols I. and II.
Ray Society.
Bibliography of the Tunicata, 1469 — 1910. J. Hopkinson.
Ray Society.
Schmidt's Atlas der Diatomaceen-kunde. 4 Vols.
Light. (For Students ) Edwin Edser.
British Rust Fungi. N. B. Grove.
LIST OF BOOKS PRESENTED SINCE JANUARY 1913.
Presented by the Author, Dr. Eugene Penard :
Nouvelles recherches sur les Amebes du Groupe
Terricola.
Presented by the Publisher, John Murray :
Problems of Life and Reproduction . . Marcus Hartog.
Presented by J. Burton :
Das Phytoplankton pes Susswassers.
358 FORTY-EIGHTH ANNUAL REPORT.
Presented by the Author, Henry Whitehead.
British Freshwater Leeches.
Presented by Prof. Arthur Dendy :
Classification and Phylogeny of the Calcareous
Sponges . . . Arthur Dendy, D.Sc., F.R.S., and
R. W. Harold Row, B.Sc.
With a reference list of all the described species systematically
arranged.
Presented by the Author, Charles Janet, Limoges :
Le Volyox and Other Papers.
Presented by the Authors, E. Heron-Allen and A. Earland.
Clare Island Survey : Royal Irish Academy.
Part 64, Foraminifera.
Presented by the Author, J. W. Gordon :
Diffraction Images.
Daring the year ending December 1913 the Library has
received the following publications :
Quarterly Journal of Microscojncal Science.
Victorian Naturalist.
Mikrokosmos.
Royal Microscopical Society.
British Association.
Royal Institution.
Geologists' Association.
Manchester Literary and Philosophical Society.
Hertfordshire Natural History Society.
Birmingham Natural History and Philosophical Society.
Botanical Society of Edinburgh.
Glasgow Naturalists' Society.
Croydon Natural History Society.
Indian Museum (Calcutta).
Royal Society of New South Wales.
American Microscopical Society.
Smithsonian Institution.
Academy of Natural Science, Philadelphia,
FORTY-EIGHTH ANNUAL REPORT. 359
Missouri Botanic Garden.
Philippine Journal of Science.
Bergen Museum.
Lloyd Library, Cincinnati.
United States National Herbarium.
Royal Society. Series B.
Natural History Society of Glasgow.
Zoologisch-botanischen Gesellschaft, Wien.
Redia.
United States National Museum.
Nuova Notarisia.
Nyt Magazine.
Liverpool Microscopical Society.
Nova Scotian Institute of Sciences.
Royal Dublin Society.
University of California.
Illinois State Laboratory of Natural History.
Societe Royale de Botanique de Belgique.
Brighton and Hove Natural History and Philosophical
Society.
Essex Naturalist.
Edinburgh Royal Botanic Garden.
Northumberland and Durham Natural History Society.
Torquay Natural History Society.
There were twelve Excursions during the year, which were well
attended, the average number present being 20'8. That to the
Botanic Gardens had the most numerous visitors, namely 35,
and second to that the grounds of Syon House, Isle worth, with
33. Though no new species appear to have been recorded at the
outings, abundant and interesting material was acquired, and as
always the Excursions were marked by a spirit of comradeship
and social friendliness, as well as being an opportunity for
scientific acquisition. It may perhaps be pointed out that scarcely
as much use is made of the results of the excursions on the
subsequent Gossip Meetings as is desirable. Our thanks are due
to the officers of the Botanic Gardens, the East London Water
Works, and the Surrey Commercial Docks, for their kindness in
allowing the Club to visit their enclosures for collecting, and
to the Duke of Northumberland for permitting, through the
360 FORTY-EIGHTH ANNUAL REPORT.
kind intervention of his agent, the successful visit to the grounds
of Syon House. The objects exhibited at the Gossip Meetings
have been interesting and sometimes noteworthy, but it may be
well to impress upon new members, and beginners especially, that
all should make an effort to bring a microscope and some object
for display on these occasions. Not only is this a duty owed
to their fellows, but a distinct advantage to themselves; they
thus become expert in the use of their instruments and in the
arrangement of their specimens.
The work of the Curator, carried on for so many years, recently
under great difficulty owing to ill health, and to the insufficient
space at his command, is beyond all praise, and the best thanks of
the Club are hereby tendered to him for his self-denying labours.
The Curator reports that all slides and apparatus in his charge
are in good condition, and during the past year a great deal of
time has been spent in revision and amalgamation of the collec-
tions. There has been a considerable increase in the number
of preparations borrowed, upwards of 2,000 having gone out, and
even then the number has been unavoidably restricted owing
to cramped storage accommodation. 192 slides have been added,
72 of them by purchase. The beautiful physiological prepara-
tions, accompanied by descriptive letterpress and illustrations,
issued by Dr. Sigmund, of wThich six series have been added,
have been in great request. A gap has been filled by the
presentation of a series of slides, with illustrated description, by
Mr. Whitehead, of Turbellarian Worms, a group previously un-
represented in the cabinets. A type collection of Hydrozoa,
presented by Mr. Harris, has been put to practical use, and, now
that his accompanying paper has been printed in the Journal, is
likely to be still further in demand. It is hoped by the issue of
additional descriptive sets to still further increase the usefulness of
the cabinets from an educational point of view. With the kind
co-operation of Mr. Vogeler the Curator has been able to issue a
supplementary list of part of the botanical preparations added
since the general catalogue was printed. The hearty thanks of
the Club are due to Mr. Vogeler for his kind services in printing,
also to Mr. Bestow for general assistance rendered the Curator,
and to the various donors of slides. The Committee desires to
thank the officers generally for the interest they have evinced,
and the often hard work they have undertaken in carrying on the
FORTY-EIGHTH ANNUAL fcEPOfct. 361
business of the Club so successfully. The thanks of the Club are
due to the editors of The English Mechanic and of Knowledge
for the reports of the proceedings published in their papers.
Finally the Committee feel that the Club may look forward
with all confidence to the future. Enthusiasm and work are
the means for continuing and increasing the success that has
attended it from its commencement, and also the means of
enabling us next year to celebrate the Jubilee of its foundation
in 1865, by men some of whom happily are still with us to
note with pride the growth and vitality shown by the Club
they inaugurated almost half a century ago.
362
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A NEW OBJECT GLASS BY ZEISS, AND A NEW
METHOD OF ILLUMINATION.
By Edward M. Nelson, F.R.M.S.
{Read March 24///, 1914.)
Figs. 1-3.
As Object Glass upon an entirely new plan has been brought
out by the firm of Carl Zeiss. This lens has not yet been
catalogued, but as it will undoubtedly effect a considerable
change in the construction and use of microscope objectives a
short account of it may prove of interest to the Club.
The object glass is a short tube oil- immersion 1 of "9 1ST. A.
Upon taking it out of its black box the first thing that will be
noticed is that it is nickeled all over, and the next is that the
front lens is set in a push tube, and not screwed up as usual ;
these two new departures from the usual type are also found in
the oil-immersion TVth recently issued by this firm.
In very early times objectives were made on this plan. Both
Ross and Smith, before 1840, used to screw the front lens to a
tube, which was pushed on to another holding the back lenses ;
this tube was then rotated until the best point was found, when
a small screw was put in at the side to keep the tube in that
position.
This form of construction has gone on continuously to the
present day, especially in the cheaper series of objectives, while
the more expensive ones, including oil-immersions, have had the
cells holding the lenses screwed into their proper positions. But
this type of objective, so far as I am aware, for an oil-immersion
is quite new, as also is an oil-immersion with a N.A. of less than
1'0. Now with regard to the performance of this lens, the
corrections are very perfect ; although no fluorite is used in its
construction it is very nearly apochromatic, and shows a consider-
able advance over semi-apochromatism, for only a slight trace of
outstanding blue can be seen.
The defining power of this objective is quite remarkable, for it
surpasses all object glasses of similar aperture I have seen.
On a M oiler's Probe-platte of 60 diatoms all are resolved except
Journ. Q. M. C, Series II.— No. 75. 26
364 E. M. NELSON ON A NEW OBJECT GLASS BY ZEISS,
the two specimens of Amphipleura pellacida. The next most
difficult diatom to the Amphipleura is the Nitzschia curvula, and
as this diatom counts 89 thousand per inch it shows what this new
lens can do with oblique light and a stop, the illuminant being
an ordinary microscope paraffin lamp with a \ in. wick. With
axial light, without any stop, the Brazilian Lindheimeri is dotted.
On M oiler's Typen-platte, with 400 forms, the Nitzschia curvula
(there called the JV. sigmatella) is very thin and difficult, and the
lens fails to resolve it, but it easily resolves all the others on that
line except the Homoeocladia Martiniana, which is more difficult
than A. pellucida. It resolves the N. crassinervis on that plate
quite easily, and it will just show the striae on the Grammatophora
oceanica, which counts 88 thousand to the inch. This diatom is
probably the G. subtilissima ; anyhow, it is very much finer than
the diatom of the same name on the Probe-platte.
The image given by this new lens of the Poclura scale is very
fine indeed. Undoubtedly in this new objective we have a lens
of great beauty and power. An important question arises as to
the influence this lens will have upon our battery of objectives.
In former times a 2 in., 1 in., a | in., a | in. and ^ in. or
yg- in. represented a full battery, but now we may have a
battery consisting of only a | in. and an oil-immersion TV in.
Here the gap is very wide, and the new lens will fill it very
satisfactorily.
This lens will, to a certain extent, supersede the oil-immersion
TV in. in medical schools and colleges. It is sufficiently powerful
to do all that is wanted in practical study, but necessarily in
research work a TV in. of wider aperture is required. For a
student it will be especially valuable, for it has of course more
working distance and a larger field than a TV in.
Another very important point is that, because of its great
working distance, it does not pick up by capillary attraction an
unfixed cover-glass. This is a source of great trouble when
working with a -— in.
Zeiss supply a funnel for reducing the aperture of this objec-
tive, so that a dark ground may be obtained with an ordinary
dry condenser and a stop. Of course with an oil-immersion
condenser no funnel is required.
Henceforth, for research work, a perfect battery will consist of
a 2 in., 1 in., | in., ^ in., this iin., and a TV in. oil-immersion.
AND A NEW METHOD OF ILLUMINATION. 365
In the Navy, when Dreadnoughts were introduced, old-fashioned
battleships were scrapped ; so also in microscopical affairs those
who are wise will scrap all their dry lenses of powers higher than
3 in. or ^ in.
One can foresee that the advent of this new lens means much,
for just as oil-immersions have eclipsed water-immersions, so will
this new lens supersede the wide-angled dry lens, which cannot
compete with it in working distance, quality, field, or price.
It is to be hoped that Zeiss will issue an objective of this class
for the long as well as for the short tube. The most notable
feature in this new object glass is the near approach that has
been made towards apochromatism without the use of fluorspar.
There is, however, another matter for your notice — viz. an
entirely new way of using an object glass for diatom or other
a
Fig. 1.
resolutions, a method, moreover, for which this new object glass
is peculiarly suited. The method is so simple that it can be
explained in a few words : (1) Place the diatom so that the striae
to be resolved are vertical in the field. (2) Set up a critical
imawe with the edge of the flame in focus and central to the
field, and open the diaphragm to its full extent. (3) By means
of the substage centring screws move the condenser so that the
image of the flame lies just outside the field of a high-power
eye- piece (fig. 1). If the striae are within the grip of the object
glass they will be resolved.
It just amounts to this, that if one is working at diatoms
with critical illumination and has need to resolve one, all that is
necessary is to move the side way adjusting screw of the substage
and place the flame image just outside the field, and the thing is
done in an instant, without any trouble with stops, slots, or
other apparatus.
You will notice that the amount of the displacement of the
condenser is very small (say twice the length of a Kavicida rhom-
366 E. M. NELSON ON A NEW OBJECT GLASS BY ZEISS.
boides), so that this new kind of illumination must not be
confused with that from a condenser considerably decentred,
with the illuminant so placed that the light passes through the
condenser obliquely, a form of illumination old and well known,
or rather which used to be well known.
Although there is no difficulty in executing the necessary
manipulation, the explanation of how the result is obtained is not
so easy. First, no direct light from the flame enters the field, but
it must be remembered that it is not a dark-ground image we are
dealing with ; for if it were high resolution would fail, as Mr.
W. B. Stokes has pointed out. The field is not dark, neither is it
light, but it is a sort of glow ; from whence does this glow come ?
At first it was thought that it must arise from internal reflections
in the front lens of the object glass, and that the lens was acting
Fig. 2. Fig.
3.
as its own lieberkiihn, as in fig. 2. But further experiments have
proved that this is not the case ; no doubt some light may travel
in that manner, but the amount that does so is quite small, and
wholly insufficient for the purpose. The main body of this light
is present owing to spherical aberration in the condenser, which
gives rise to a very oblique beam, as in fig. 3. For this kind of
illumination therefore a condenser with spherical aberration is to
be preferred to one more aplanatic.
There can be no question about extraneous light from the
illuminant having anything to do with it, for when a metal
screen, with a slit the size of the edge of the flame, was placed
close to the chimney, no difference in the effect was observed.
This kind of illumination will be of service, for it will enable an
observer to obtain high resolution with a dry condenser, in an
instant, without the troublesome manipulations usually necessary.
Journ. Quekett Microscopical Club, 8a: 2, Vol. XII., No. 7"», November 1914.
307
A NEW LOW-POWER CONDENSER.
By Edward M. Nelson, FJR.M.S.
{Read April 28a, 1914).
Fig. 4.
Some time ago 1 pointed out to the Club that microscopists were
badly off for a low-power condenser, for, so far as I know, there
is no such appliance to be had. Mr. Curties kindly exhibits-
to-night one he has made from my formula. This condenser is
designed as a low-power illuminator, and not at all for the
purpose of resolving fine diatom striae. With the top on, its
focus is 1 inch, and with the top off 2 inches.* Both the lenses
are achromatised, and it will be seen that it is particularly
achromatic, as well as aplanatic ; it will work from the lowest
powers up to a | inch.
The first object I examined with it was a Navicula lyra, with
a Zeiss 12 mm. apochromat. I have been working with the
microscope now upwards of forty years, and never before have I
seen such a perfect image of this diatom. In general work,
with the lower powers, the flat of the flame of a reading
lamp is focused upon the object ; this with the 2 inch condenser
covers a large portion of the field, even of the lowest powers. It
will give an excellent dark-ground for pond life, etc., up to say a
| inch objective. This condenser is to be named " Quekett,"
after that illustrious microscopist.
Speaking of dark backgrounds, there is a great defect in many
condensers, viz. that the spot is not centred to the optic axis of
the condenser, because the cell holding the stops is not placed
accurately on the mount. This is a serious defect, because if the
stop is not centred, the microscopist is forced to use a much larger
* This back lens of 2-inch focus when used by itself in a holder forms
the best "verant" I have seen. It is very useful for the examination
of large microscopical objects, as well as of flowers, engravings, coin-,
postage stamps, seals, etc.
368
E. M. NELSON ON A NEW LOW-POWER CONDENSER.
stop than is necessary.* How often one sees a dimly lighted
object, with a halo of bright fog, on one side of the field, owing
to the use of an excentric stop larger than is necessary.
To remedy this defect, Mr. Curties shows a simple centring
stop-holder made from my design. The stop consists of a disc
with a hole in it which fits on a pin B ; this I designed for my
Jubilee microscope, which was made by Powell and exhibited at
the Club in 1887.
Why microscopists will have their stops cut out of the sheet, a
much more expensive plan than a disc fitting on a pin on a spider,
ZI
v
Fig. 4.
A, lever ; B. flat tube with the stop on pin ; C shows the flat tube placed
on the lever, with screw for fixing the appliance beneath the iris-box.
I am unable to tell you. But to return, this pin is fixed to the
end of a flat tube B, which slides on a flat bar A ; this forms the
centring adjustment right and left. The centring adjustment
rectangular to this is in arc, by moving the arm C, which is
pivoted below the iris box.
* If, for example, a centred stop of -4-inch diameter is requisite, and
supposing that the stop carrier is 1 inch out of centre, then a stop of
•6 inch will be required to do the same work as the stop of *4 inch. Now
the area of a circle of "6 inch diameter is more than double that of a circle
•4 inch diameter ; this shows the great loss of light an excentric stop-holder
causes.
Journ. Quek-ett Microscopical Club, Scr. 2, Vol. XII. , No. 75, November 1914.
369
BINOCULAR MICROSCOPES.
By Edward M. Nelson, F.R.M.S.
(Bead. May 2tth, 1914.)
Fig. 5.
In recent years several binoculars have been introduced ; none
of them, however, can be called new. The first, the Greenough,
by Zeiss * in 1897 was a twin microscope, a form of binocular
invented by Pere Cherubin d'Orleans nearly three hundred years
ago. The second, by F. E. Ives in 1902,f is very similar to one
designed by Wenham in 1866 as a counterblast to Powell's
high -power binocular in which the whole beam is sent into
each eye. % The third is a modification of the second by Messrs.
Leitz,§ and the fourth, by Messrs. Beck, is very similar to that
of Ives.
Before proceeding, let us enumerate the points gained by
binocular vision. They are four in number and were stated
by me in the English Mechanic || as follows :
1. Stereoscopism, or the power of appreciating solidity.
2. Increase of apparent magnifying power.
3. Increase of illumination.
4. Increase of colour perception.
The first binocular we have to deal with, viz. the Greenough
twin microscope, became a practical form owing to the re-
introduction of the Porro prism by C. D. Ahrens in 1888.
Obviously, it can only be used with very low powers, but never-
theless I have had no reason to alter the favourable opinion
I expressed for this form of binocular when it was first ex-
hibited by Messrs. Zeiss. In this instrument all the above
* Journ. B.M.S., 1897, pp. 599-600.
t Ibid., 1903, p. 85, Fig. 3.
X I am indebted to Mr. Rousselet for kindly bringing the Ives binocular
to my notice.
§ Journ. B.M.S., 1914, p. 5.
|| 1911, Vol. 94, No. 2432.
370 E. M. NELSON ON BINOCULAR MICROSCOPES.
four attributes of binocular vision are secured. In tins micro-
scops the left-hand view of the objective is sent into the left
eye, and the right-hand view into the right eye; this, because
of the erection of the image, gives an ortho-stereoscopic image.
If the microscope had been of the ordinary inverting type the
image would have been pseudo-stereoscopic. It was due to
ignorance of this principle that several of the early bino-
culars were pseudo-stereoscopes. One of the most important
points in this, as well as in all forms of binoculars, is that
the images should be accurately superimposed. Several tests
have been proposed ; one was that an object should be
placed upon the stage, so that it should just touch, say, the
right edge of the field of the right-hand eye-piece. This eye-
piece is then transferred to the left-hand tube, and if the object
still touches the same portion of the field with the same eye-
piece the adjustment was supposed to be correct. But this
is no test at all, for it tells you nothing about the really
important question, which is whether the discs of the fields
are themselves superimposed.
The best test for a Greenough is to oscillate rapidly a strip
of card half-inch wide before the fronts of the objectives. If
the images shake, then they are not accurately superimposed,
and the objectives require readjusting in their seats.
Leaving now the twin microscope, we will pass on to the
other kind of binocular, which has only one objective. In the
Wenham this important adjustment is performed by the align-
ment of the tubes, for the tilt of the prism has very little
effect, but its edge must be carefully set at right angles to
a line joining the centres of the eye-pieces.
The single objective binocular may be divided into two kinds,
viz. those of the Wenham or Stephenson type, which split the
beam at the back of the objective, and those of the Fowell type,
which pass the whole beam. All those of the Wenham type
possess the first of the attributes enumerated above, viz. stereo-
scopic effect, for in an ordinary inverting microscope, at the
left-hand eye-piece the Ramsden disc will be a miniature of
a cross-section of the beam issuing from the right-hand half
of the objective, and that at the right-hand eye-piece from the
left-hand half of the objective, the inversion of the image
necessitating a cross-over of the pencils, for if there were no
E. M. NELSON ON BINOCULAR MICROSCOPES. 371
cross-over the image would be pseudo- stereoscopic. There is
no cross-over in a Stephenson, but then it is an erecting
microscope.
The binocular of the Powell type, which passes the whole
pencil, does not possess the first attribute of stereoscopism : the
image in both eyes being identically the same. No doubt,
owing to the employment of both eyes and for physiological
reasons, there may be more or less of a stereoscopic effect, but
that is an entirely different thing from true stereoscopism.
When, for example, the full moon is observed through a field-
glass it appears as spherical as a cricket-ball, the images in
each eye must be identical and no true stereoscopism can be
present.
If half the Kamsden's disc above the eye-lens is stopped out
by a diaphragm, so long as the cross-over is preserved, the
image in an inverting microscope will be ortho-stereoscopic. This
was mentioned by "Wenham in 1854; and later, in 1882, Dr.
Mercer pointed out that a diaphragm is not needed, but an
ortho-stereoscopic effect may be obtained by making the inter-
ocular distance less than the interpupillary, which causes the
iris of the pupil of the eye to cut off the inner half of the
Ramsden disc.
The disadvantage of a diaphragm above the eye-piece is that
it occupies the same place as that in which the eye ought to be;
and the disadvantage of Dr. Mercer's method is that the head
and eyes must be kept absolutely steady, otherwise there will be
a flickering of the image, which causes strain and distress to
the eyes : the higher the power, the smaller the Kamsden disc
and the greater will be the flickering and strain and fatigue
to the eyes. For these causes ortho-stereoscopism in a binocular
of the Powell type is of a different character from that of the
Wenham or Stephenson type. In books dealing with this
subject the Wenham super-eye-piece diaphragm and the Mercer
narrow inter-ocular distance are treated as alternative plans,
equal in efficiency to the Wenham divided objective method.
Such, however, is not the case. It is only necessary to place
two microscopes alongside each other, charged with similar
objectives and powers, one having a Wenham divided objective
and the other a Mercer narrowed inter-ocular distance, when
an examination of the same object will at once dispel any theory
372 E. M. NELSON ON BINOCULAR MICROSCOPES.
as to the equality of the results, the ortho-stereoscopism in
the Wenham being superior to that in the other.
In the Wenham and Stephenson, ortho-stereoscopism is weak
with objectives which have less than 20° of angular aperture (say
1^ inch of *17 N.A.), and the divided objective breaks down with
high powers. A divided objective binocular may be said to be at
its best with a \ inch ; good with 1 inch, |, T4(j-, and g ; fair with \ ;
but failing with a 4. Very small Wenham prisms have been
made and mounted on a funnel and placed in the mounts of a
Y2- ', the result being so indifferent that further experiments
in that direction were abandoned.
The Wenham plan possesses a great advantage over all other
kinds of stereoscopic binoculars, viz. that the straight tube is
free from glasses, prisms, or other appliances likely to disturb the
image. You will naturally ask, Why then was -the Powell non-
stereoscopic system introduced ? The answer is that it was
intended to come in where the W'enham left off, for Powell
engraved on his Wenham prism, " For Low Powers," and on his
own prism, " For High Powers." The reason why the high-power
prism fell into disuse was on account of the poor definition that
could be obtained with it. It bad no clear tube like the Wenham,
and it should be remembered that prisms and flat glass surfaces,
owing to the manufacture of prism field-glasses, are now made
with a precision and accuracy altogether unknown in 1865, when
Powell made his.
Binoculars of the Wenham or divided lens type have the dis-
advantage of indifferent definition of objects placed vertically
in the field. If, for example, that well-known test for medium
powers, the hair of the Polyxenus lagurus, be placed vertically in
the Wenham, with, say, a one-third objective, the definition
will be fuzzy ; but directly the hair is placed horizontally in the
field, the image becomes sharp. In ordinary work with a
Wenham, where an ortho-stereoscopic image is of primary im-
portance, this defect is not noticed, and probably only a few
raicroscopists are acquainted with it. But with the Powell type
of binocular, this error does not exist. The image is the same
in all azimuths. Now, in the Wenham high-power binocular,
which was introduced in reply to Powell's, the beam was divided
by two right-angled prisms with an air-space between tbem, the
inclination of the surfaces being adjusted near to the critical
E. M. NELSON ON BINOCULAR MICROSCOPES. 373
angle so that some of the light was passed while some was
reflected. As this took place at both surfaces a double image
was made in one tube, which, of course, was fatal to the design,
and the binocular never came into use. Prof. Abbe's binocular
eye-piece was made on a similar plan and failed for the same
reason. Subsequently, however, a method was discovered for
depositing a semi-translucent film of silver on glass, by which
means a beam could be half reflected and half transmitted. This
method was adopted by Ives, and the doubling of the image in the
one tube was avoided. The Ives binocular resembled the Wenham,
inasmuch as the prism could be withdrawn and the instrument
used as a monocular. But it also differed from it, for in the
Wenham the inter-ocular distance was adjusted by lengthening
or shortening the draw-tubes, while in the Ives it was accom-
plished by a lateral displacement of the side tube in arc, the
lower end of this tube being pivoted on a hinge. This was
a good design, for it permitted the inter-ocular distance to be
adjusted without disturbing the tube length. In 1860, when the
Wenham was first introduced, low powers, with their double
fronts, were very insensible to alteration of tube length, and as
all powers higher than a | had correction collars, any alteration
of tube length was of no moment ; this, however, no longer
applies, because objectives now made with single fronts having
over-corrected backs are very sensitive to tube length. So in
designing a binocular for use with such objectives, particular
attention must be given to tube-length adjustment.
Now, lately, Messrs. Leitz have brought out a new binocular of
the Powell type ; the arrangement of the prisms, which deflect the
rays right and left, differs from the many kinds that have been
invented for this purpose. The semi- translucent silver film
method has been adopted by Messrs. Leitz in their new binocular,
and an almost equally illuminated image is seen in each tube.
By means of their very perfect system of working prisms they
have secured a really sharp critical image in each tube. The
tubes are parallel to one another, but the instrument cannot be
used as a monocular, for neither body is in the optic axis of the
objective. Messrs. Beck have also brought out a binocular
microscope with the two Ives prisms joined in one. The bodies
are converging, but as one body is in the optic axis of the
instrument, it can be used as a monocular.
374 E. M. NELSON ON BINOCULAR MICROSCOPES.
A great deal has been made of the difference between parallel
and converging tubes. It has been urged that parallel tubes are
conducive of eye strain and fatigue. Having now had a Leitz
microscope in constant use for nearly three months, and having
done prolonged work with it, no more eye-strain has been found
with the parallel tubes than with a Wenham, and with both
there is less fatigue than with a monocular.
To me the image plane in a microscope appears at so definite
a distance that I seem able to hold a pencil in front of it, or
behind it, or touching it. When using a binocular I simply look
at the image in this plane, being quite as unconscious of either
the parallelism or convergence of the eyes as if I were looking at
various objects in the room, or on the table. During the course
of these experiments several curious observations were made.
Various persons were asked to examine the images in the Wenham
and in the Leitz for the purpose of ascertaining their opinion as
W M
Fig. 5,
to the relative amount of stereoscopic effect in each. Two persons
having good normal vision saw no stereoscopic effect in either,
the images in both instruments appearing quite flat ; one of them
could see no stereoscopic effect either in an ordinary stereoscope
or in a field glass. Two others saw stereoscopism in the Wenham,
but not in the Leitz with the Mercer method. With the same
object and same power in both (| inch and B eye-piece), most
persons said that stereoscopism was stronger in the Wenham,
owing probably to want of practice and experience with the
Mercer method.
When the inter-ocular distance in the new binocular is kept
of the same width as the inter-pupillary, the microscope is a
non-stereoscopic binocular. The Mercer plan of reducing the
inter-ocular distance is found to produce fatigue on account of
the flickering of the image when the Ramsden disc is small.
Figure 5 shows the reason why eye strain and fatigue,
which are present with the Mercer method, are absent with
E. M. NELSON ON BINOCULAR MICROSCOPES. 375
the Wenhani ; the circles in W and M represent the pupil of
the eye, the semi-circle in W is the Ramsden disc in a Wenham,
and the portion of the circle in M is the Ramsden disc when
the inter-ocular distance is less than the inter-pupillary in the
Mercer method. It can at once be seen that a slight movement
of the head will not affect the luminosity in W, but in M the
head cannot be moved in the slightest degree without either
increasing or diminishing the amount of the Ramsden disc
cut off by the iris of the pupil ; necessarily, therefore, if in one
eye the Ramsden disc is enlarged it is cut off in the other eye,
and vice versa, which is the cause of the nickering previously
mentioned. A moment's consideration will show how this defect
in the Mercer method may to a certain extent be minimised.
Obviously the larger the Ramsden disc the less noticeable will be
this defect. This, of course, points to the use of a low-power
eye-piece with any given objective. The low-power eye -piece
has an additional advantage — -viz. that the rays emerge at a
smaller angle than in the case of a deep eye-piece, and this
permits the eye being held at a little distance from the proper
eye-point, where the Ramsden disc is expanded. Hence the
rule for stereoscopism with the new binocular is to make the
inter-ocular distance somewhat less than the inter-pupillary, and
not to use eye-pieces deeper than 1| inches, and to hold the eye
a little way behind the eye-point.
There are two other sources of eye strain and fatigue common
to all binoculars of whatever type : the first is non -coincidence
of the superimposed fields. This by no means uncommon fault
is due to carelessness in fitting and putting together ; it is a
source of great eye strain and fatigue, and the purchaser of a
binocular microscope should be particular to see that the fields
are precisely superimposed. The second is a difference of foci
in the tubes. In the binoculars both of Messrs. Leitz and Beck
provision is made for this by a focusing arrangement in one of
the eye-tubes. In the Greenough it is accomplished by means
of a focusing adjustment in one of the objectives. If, therefore,
a microscope is provided with some such arrangement, the user
need not be troubled about this point.
Passing on now to the second attribute of a binocular — viz.
that of increased apparent magnifying power, it is found to be
as obvious in a microscope as it is in a field glass. Its precise
376 E. M. NELSON ON BINOCULAR MICROSCOPES.
amount is difficult to determine, nor is it known if it is the
same for all persons. As I pointed out elsewhere, it is inaccurate
to say that there is an increase of apparent magnification in a
binocular ; what really takes place is that in a monocular there
is a diminution of apparent magnifying power, and that this dimi-
nution is non-existent in a binocular. If any one examines a
lighthouse, a ship, or other object with a 2 or 3 power monocular
telescope, the image appears no larger than when it is seen with
the naked eye. The image, as any one will tell you, is brighter
and clearer, but not larger. Directly the image seen in the
telescope is superimposed on that seen with the other eye the
magnification of the monocular is demonstrated, which generally
causes surprise. Having given this subject considerable attention,
I am of opinion that the true magnification is seen in a binocular,
but that with a monocular, either telescope or microscope, this
is reduced.
The third attribute — viz. illumination : It is doubtful if there
is much gain in the Greenough type of binocular, as the amount
gained by the use of both eyes is probably lost owing to
the prisms, surface reflections, etc. Of course, with a single
objective type of instrument there must be a loss. This is of
no importance, for in a microscope one has usually more light
than is needed.
The fourth attribute : Experiments have shown that colour
tints are increased in a binocular ; this is a distinct gain, for
there is always much and often total loss of colour in micro-
scopical observations.
There is another form of binocular which must be mentioned,
viz. the binocular eye-piece. This was an early invention of
Wenham ; the next to take it up was Tolles, of Boston, U.S.A.,
who made a very good one by using prisms on the Nachet
plan, dividing the beam by means of an isosceles prism. Tolles'
binocular was well made, stood deep eye-pieces, and had the
advantage that both tubes were similar ; consequently the illumi-
nation and path of the rays was equal in each. The advantage
this system possesses is that it permits of objective correction by
draw tube. With other binoculars objective correction is not so
easily accomplished.
The last form of binocular eye-piece was brought out by
Professor Abbe. This, as we have seen above, was a failure.
E. If. NELSON ON BINOCULAR MICROSCOPES. 377
There was another objection, viz. that the path of the rays was
much longer in one tube than in the other, so that two different
forms of eye-pieces had to be used. Very few were made, and
it is probable that no more will be.
In conclusion let us examine the position of these new
binoculars. From what has been said above they are clearly a
class by themselves. It would be quite inaccurate to entertain
the idea that these instruments are a new kind of stereoscopic
binocular constructed to enter into competition with, and finally
to supersede, the existing binoculars of the Wenham and
Stephenson types ; for from what we have seen they only possess
the first attribute, viz. stereoscopism in a limited manner. The
word "limited" is used in default of a better expression. It
does not mean that with the Mercer effect stereoscopism becomes
less strong, for, on the contrary, with the Mercer effect hyper-
stereoscopism is often present, and care should always be taken
to guard against it. With the Mercer effect a cell, for example,
which is, and which under a Wenham would look, like an
ellipsoidal football will appear under a hyper-stereoscopic Mercer
effect as if standing on end.
The centre of that beautiful diatom, plentiful on " Mud
Cuxhaven " slides, viz. Actinocyclus Ralfsii, under hyper-stereo-
scopism appears at the bottom of a deep pit, the outer annulus
being highly raised,* whereas we know that the structure is a
kind of shallow saucer. The word "limited" is intended to
apply to the stereoscopic condition that the Itamsden disc cannot
be centred to the pupil. The Mercer plan also entails loss of
light and of resolution of vertical striae. Messrs. Leitz provide
their inter-ocular adjustment with a millimetre scale. The
observer should carefully note the precise adjustment that will
centre the Ramsden disc to his own eyes ; half a division on the
scale (which represents 1 mm.) or even less ought to suffice for
the Mercer effect. The test of coincidence of the inter-ocular
with the inter-pupillary distance is that of maximum brightness.
Luminosity quickly falls off with either increase or decrease of
inter-ocular distance. With a little practice, one becomes so
expert in judging the luminosity that a reference to the divided
scale is seldom necessary.
* Seen best with transmitted light, a No. i objective and a 1 inch
eye-piece.
378 E. M. NELSON ON BINOCULAR MICROSCOPES.
You will then naturally ask, If these new binoculars are not
stereoscopic, what is their use? Their use is confined to the
employment of full Kamsden discs in each eye, that is for
work with non-stereoscopic images. An enormous amount of
microscopic work is done with images of that kind, and when
prolonged work is undertaken with the new binocular great
relief and comfort to the eyes will be secured. But to say, on
the one hand, that one of these instruments when used for,
say, the examination of pond life with a \ inch and the Mercer
effect is going to supersede a Wenham, and on the other hand
to state that by means of this new binocular delicate secondary
structures on diatoms will be more easily seen than with a
monocular, is to talk nonsense. At the upper limit they cannot
compete with the monocular, and at the lowest limit they cannot
compete with the Wenham ; but in their own sphere they are
extremely useful and form a very important addition to the
modern improvements in Microscopy.
At any time with the new binocular the Mercer effect can be
turned on to determine the relation of the various parts of an
object ; but it must be borne in mind that stereoscopism in a
microscope with the higher powers is only partial, and whether
it is present or not depends largely upon the nature of the
object; for example, with a medium power, such as \ or a
i, the rays of a Heliopelta will exhibit strong stereoscopism,
but many other objects with the same power will show none.
With a \ and a spread slide of P. angulatum, it is difficult to
determine whether a valve is convex or concave side up. Stereo-
scopism in macroscopic vision differs from that in microscopic
vision inasmuch as it is influenced greatly by the thickness of
the object.
With macroscopic vision stereoscopism is seen equally well
with either a book or a bookcase, but that is not so with
microscopic vision. In that case stereoscopism would be present
with our allegorical bookcase but not with the book. Low
powers deal with thick, coarse objects, and therefore stereoscopism
is present ; but with the higher powers it is necessary to select
suitable objects for the demonstration of the stereoscopic effect.
For instance, bacteria dried on cover do not exhibit any more
stereoscopism with the new binocular than with a monocular,
for in a monocular they can be made to look like sausages ; but
E. M. NELSON ON BINOCULAR MICROSCOPES. 379
when bacilli in tissue are examined with the Leitz binocular, a
^ and the Mercer method, a beautiful picture of them in
perspective projection will be seen as well as of the cell nuclei
which appear spherical as marbles.
It is a good plan when working with this new binocular to
turn on the Mercer effect and when the form of the image has
been mentally grasped to turn it either wholly or partly off,
for when the stereoscopic form of an object has once been
realised by the mind re can be retained, although the optical
conditions which gave rise to it have been removed. Some will
have noticed, when looking at parquetry representing cubes, that
if the effect when first noticed is intaglio it is a matter of some
difficulty to reverse this mental image so that the cubes shall
appear to be in alto-rilievo.
I asked Messrs. Leitz to make me a couple of tubes to slide
over their tubes, by which means tube-length adjustment can
be accomplished. The tubes can be drawn up and down over
the fixed tubes and the eye-pieces also can be partially drawn
out, as the tubes are sprung both top and bottom. Without
these tubes it was not possible to obtain a critical image with
Messrs. Leitz' own objectives for the Continental short tube.
The great charm in these new binoculars consists in the
sharpness of the image combined with ease and comfort of vision,
hence the need for lens correction either by alteration of tube
or by screw collar. The sharpness of image in my instrument
at least is very little behind that of a monocular, for it requires
a delicate test to perceive any difference at all, and often a pair
of 18 compensating eye-pieces have been used with advantage.
With a ^ inch objective and upwards, these new binoculars
have the field all to themselves, as no other binocular for sharp-
ness and crispness of image can for a moment compete with
them. With low powers and 1^ inch eye-pieces and a slight
Mercer effect they give lovely images, but, as was hinted above,
with the Mercer effect one must alwaj^s be on one's guard against
hyper-stereoscopism. Recently a shock was experienced on finding
that a Radiolarian which appeared under the Mercer effect as
round as an orange, when viewed on edge was shaped rather like
a mince pie. Here the Wenham gave the truer image.
Latterry, even the Greenough, which is known to give beautiful
images, has been suspected of hyper-stereoscopic tendencies.
Journ. Q. M. C, Series II. — No. 75. 27
380 E. M. NELSON ON BINOCULAR MICROSCOPES.
I never expected to live to see a critical image of a Podura
scale in a binocular, but that is now an accomplished fact, for I
have seen a most beautiful picture of a Podura scale with the
Leitz binocular and an apo 4 mm., and that, too, critical in all
azimuths.
Dark-ground images are very suitable for the new binoculars
because the objective is working at full cone, so there is a larger
Ramsden disc than would be usually the case with transmitted
light.
Messrs. Leitz sent with the microscope some of their new
Orthoskop-Kellner eye-pieces, the performance of which is very
satisfactory. I have had a cap, attachable to the eye-piece by a
small screw, made to prevent the eye lens being smeared by
contact with the eye-ball. This with a binocular happens
frequently, so that a process of continual wiping of the eye-lens
is necessary, which causes interruption and much interference
with one's work.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 75, November 1914.
38]
NOTES ON THE CULTIVATION OF PLASMODIA OF
BAD HAM I A UTRICULARIS.
By A. E. Hilton.
{Head May 26*A, 1914.)
Fig. 6.
A free-flowing mass of naked and almost undifferentiated
protoplasm, such as we have in the plasmodium of Badhamia
utricularis, suggests opportunities for biological experiments,
with unusual promise of success. From living matter in so
primitive a condition, it should be possible, one imagines, to gain
a more intimate knowledge of the fundamental substance which
is the basis of all physical life.
Systematic investigations, however, depend upon a constant
supply of material, and a continuous supply of plasmodia is not
easy to obtain. In natural surroundings, they are only to be
found when conditions of temperature and moisture are suitable ;
and even then, in most districts, they are very scarce. More-
over, the removal of a plasmodium to a place suitable for
studying it, generally results in the plasmodium shortly passing
into the sporangial stage, or perishing from lack of proper
nutriment. Either way, the immediate end is defeated.
In the Introduction to Mr. Lister's Monograph of the
Mycetozoa, recently revised by his daughter, it is stated that
" The plasmodium of Badhamia utricularis is one of the very few
we are acquainted with that feed on living fungi," and that " it
is capable of being cultivated without limit on Stereum hirsutum
and allied species, and can be observed under the microscope to
dissolve fungus hyphae as the hyaline border of a wave of the
yellow plasmodium advances over them." In many places,
however, an unfailing stock of the fungus mentioned is difficult
to ensure ; so that here, again, a difficulty arises.
382 A. E. HILTON ON NOTES ON THE CULTIVATION OF
Professor De Bary (1884), in his great work on the Com-
parative Morphology and Biology of the Fungi, Mycetozoa and
Bacteria, mentions boiled cabbage leaves as having been used for
the cultivation of Mycetozoa ; but he does not name the species
which were cultivated, and boiled cabbage leaves, if kept for any
length of time, become too offensive for endurance.
In 1906, an account was published in Germany of experiments
in the cultivation of plasmodia made by J. G. Constantineau ;
and these are alluded to both in Mr. Lister's Monograph and
the Royal Microscopical Society's Journal for April 1907. In
neither of these are details given, or any indication of the
extent to which the experiments were successful. Possibly
they were too technical to be of general use. '
No apology, therefore, is needed for placing on record the
result of experiments made during the last few months, which
suggest a method of continuous cultivation of plasmodia of
Badhamia utricularis, at once simple and practicable. Whether
this method, with or without modification, is applicable to
plasmodia of other species, I have not had an opportunity of
<letermining. Other workers may perhaps take up the suggestion
and carry the matter further.
In the first place, I have found that the growth of a Plas-
modium of B. utricularis can be stimulated by the occasional
application of a mixture of ammonium phosphate * and cane
sugar, half an ounce of the phosphate and the same weight of
sugar being dissolved in a quart of water.
In the second place, I find that the plasmodium will feed and
grow on bread kept moistened with water, especially if some of
the mixture described be added to it from time to time.
The effect of the mixture seems to be both direct and indirect-
It appears to impart greater vigour to the plasmodium, so
increasing its feeding capacity ; and it also benefits the plas-
* Since the above paper was read, Mr. James Grundy has informed mc
be has added calcium phosphate to the mixture with excellent results.
PLASMODIA OF BADI1AMIA UTRICULARIS. 383
m odium indirectly by promoting the growth of filamentous
moulds, such as Aspergillus or Penicillium, which soon appear on
fungus or bread, after the mixture has been applied to it. The
hyphae of these moulds are dissolved and absorbed by the proto-
plasm as food.
In using the mixture discretion must be exercised, according to
the condition of the plasmodium, as sometimes plain water is
preferable ; but the careful observer will find sufficient indications
to guide him in this respect. No precise rules can be laid down,
but the student will find that with these auxiliary helps he will
be less dependent than heretofore on a supply of Stereum or
similar fungus, although it may be advisable to use some of that
at times, if convenient, as being the more natural food. Any
fungus which becomes putrid must be removed, or it may poison
the plasmodium ; but the bread is not so liable to become
injurious, and may remain a reservoir of protoplasm until, after
a prolonged period, the plasmodium has eaten it all.
]STote. — I have also been asked to describe, for the benefit of
our readers, my method of exhibiting the reversing currents of
streaming plasmodia, a description of which has been given in
the Journal.* The very simple arrangement is shown in the
diagram below.
Fig. 6.
A tube of this size is sufficient, and a ring of blotting-paper,
with sclerotium upon it, is placed inside ; the sclerotium being
between the paper and the glass. A few drops of water are
added, the cork is inserted, and the tube is then tilted and
revolved until the water has soaked the paper and moistened the
* Joum. Q.M.C., Vol. X., pp. 263-270, November 1908.
384 A. E. HILTON ON PLASMODIA OF BADHAMIA UTRICULARIS.
whole of the interior surface of the tube. A small hole is bored
through the cork to admit air without allowing too much
evaporation ; or the cork may occasionally be removed. If
necessary, a drop or two of water can be added now and then, to
keep the air moist. Only plain water should be used. When
the sclerotium revives, the plasmodium creeps on to the glass on
either side of the ring of paper, and the reversing currents can
then be seen by placing the tube on the stage of the microscope
and throwing the light up through it from the mirror beneath.
A 1 inch objective, focused on the veins of the spreading
plasmodium, shows the streaming movements quite plainly. The
sclerotium should be placed in the tube the day before the
plasmodium is required for exhibition.
Joarn. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 75, November 1014.
on K
85
ON THE MINIMUM VISIBLE.
By A. A. C. Eliot Merlin, F.R.M.S.
(Read October 27th, 1914.)
I have read with great interest and profit our President's
Address on " Organisms and Origins." The subject is one that
must fascinate every microscopist, whatever his line of research
may be. In the address a point was raised respecting the
minimum visible, it being stated that " it seems impossible to
obtain any precise information as to the size of the smallest
particles that can be seen with the microscope."
Now, setting aside the ultra-microscope, as our knowledge is
very exact and definite indeed on this subject, it may prove of
interest to deal with the question at some length. As a matter
of fact, when a particle properly illuminated is just visible under
a given objective, if the aperture be cut down by means of an iris
diaphragm placed above the back lens so that the particle just
ceases to be visible, and the numerical aperture to which the
objective has been thus reduced is measured, then the dimensions
of the particle can be exactly ascertained from the antipoint table
published by Mr. Nelson in the Journal of the Royal Microscopical
Society. This antipoint table should prove invaluable when
accurate and minute measurements are necessary, but little
interest has been apparently evinced in the matter since micro-
metry of a high order is no longer practised, in England at least.
Leaving this for the present, I venture to refer to and examine
the claim made by Mr. Brown at a recent meeting of the Club
that he had seen central " pores " on the surface of the frustules
of certain diatoms ; which he estimated at l/200,000th of an inch
in diameter. On reading Mr. Brown's " Notes on the Structure
of Diatoms," * I examined a specimen of Pleurosigma balticum,
* Journ. Q.M.C., Ser. 2, Vol. II. p. 317.
386 A. A. C. ELIOT MERLIN ON THE MINIMUM VISIBLE
in realgar, under a very perfect recent 1/1 2th apochromat of
N.A. 1*4, employed with a magnification of 4,200. Mr. Brown's
central "pores" could be readily distinguished at a certain high
focus on the outer layer of the valve. But in the " pores " so
revealed I immediately recognised my old friends Dr. Boyston-
Pigott's " dark eidolic dots of interference." In thus frankly
stating my conviction, I am sure that Mr. Brown, as a veteran
observer, would wish me to pursue no other course. We are all
liable to make mistakes in the interpretation of diatomic struc-
ture, and the only hope of progress lies in friendly criticism and
the exchange of views. Although I consider Mr. Brown's central
" pores " of Pleurosigma balticum, Navicula serians and P. angu-
lation! to be clearly false ghosts, it is by no means unlikely that
the outer layers of these diatoms may be perforated with fine
secondary structure, like the forms with coarser primaries.
Under the most critical conditions, with T4 N.A. and a magnifi-
cation of 4,200, something of the kind has been seen both in
P. balticum and N. serians. These appearances, however, are
far more elusive and difficult than the eidolic central clots, and
quite different in aspect and position. So far as my experience
goes, capped diatomic primaries are always pierced by at least
three or four secondaries when any such structure is observable.
It may nevertheless be safely asserted that if the primaries of
P. angulatum are thus capped and pierced, the secondaries must
be as much beyond the grasp of our best lenses as are the eidolic
dots of A . pellucida.
In order to show how similar are the observational conditions
described by Dr. Royston-Pigott as necessary for the proper
demonstration of eidolic clots to those specified by Mr. Brown
concerning his central diatomic " pores," I must quote Dr. Royston-
Pigott's remarks on the subject at some length. In "Micro-
scopical Advances " * it is stated : " With regard to attenuated
circles, nothing are more abundant in diatomic and scale
markings. If a spherule be l/60,000th of an inch, the black
marginal ring is generally about one-fifth of this, or 1 /300,000th
thick, ornamented with a minute central black clot. The clot and
its fellows are amongst the most interesting and surprising sights
in minute microscopy. Few glasses will show them. That a
* English Mechanic, vol. xlviii. p. 209.
A. A. C. ELIOT MERLIN ON THE MINIMUM VISIBLE. 387
minute spherule should be capable of exhibiting the same
recherchcs phenomena as a delicate glass lens l/30th focus solely
from its refractions and chromatic aberrations, at first seems
quite incredible." In another place * Dr. Poyston-Pigott con-
tinues : " The existence of dark eidolic dots of interference is an
important fact which now requires further elucidation. Darkness
has resulted from excessive light. Wave neutralising wave, certain
undulations killed each other. This is seen on a grand scale in
the solar spectra formed by a small lens in the foci of a very fine
microscojDe. Forty-eight dark rings have been counted developed
by an extremely small solar beam. The feeble refractions occur-
ring in a diatomic convexity cannot develop a very numerous
retinue of rings ; but sufficient diatomic lenses have been accumu-
lated for the purpose indicated. To exhibit successfully a series
of eidolic dots of interference demands very careful illumination
and a very fine objective. Their size varies with the nature and
diameter of the refracting spherule. The 1/Sth water lens of
Powell and Lealand seems to excel all my others in detecting
them in different focal planes. Six have been in order thus seen,
but in small spherules such as those of P. angtdatum many dots
are too faint for recognition. My experience of scale molecules
has convinced me they also are wonderfully transparent, display
black marginal test rings, and often one eidolic dot." . . . " These
dots are well developed by large beading of diatoms from 1/9, 000th
to 1/1 4,000th of an inch in diameter. Extremely large spherical
beads are seen in Cresswellia superba and in Cestodiscus superbus
(beads 1/1 2,500th) ; E. costatus and C oscinodisens radiatus are
also fine examples. To exhibit successfully all the eidolic dots of
interference in successive focal planes demands very excellent
glasses, careful precautions, and, above all, well-separated diatomic
beads. They may be caught above very small diatomic and scale
beading. Remarkably good eyesight has distinguished them
above the bosses of P. angulation and occasionally I have
detected two sets of dots when one stratum of beading lies just
below another. In general, except in strongly pronounced
diatomic bosses, the observer may rest satisfied with finding the
primary eidolic dot, No. 1, fig. 1 in the diagram. f A better glass
* English Mechanic, vol. xlix. p. 315.
t A diagram showing a series of eight gradually diminishing dots is
annexed to the original paper.
388 A. A. C. ELIOT MERLIN ON THE MINIMUM VISIBLE.
may enable him to detect Nos. 2 and 3 by daylight. Lamplight,
unless its yellow tint be subdued with a blue chimney and other
blue glasses, extinguishes the dot by the flame image produced by
the diatomic lens. It may be recovered, however, in front of it
by careful manipulation." ..." Dr. Van Heurck obligingly
photographed with the new apochromatic glass the eidolic dot
shown by the beading of P. angulatum."
Dr. Royston-Pigott estimates the dots in P. angulatum to be
attenuated to 1 /250,000th of an inch and considers that
extremely minute dots, about 1/300, 000th, are not only found
amongst diatoms, but reveal themselves in the transparent
headings of moth-scales, and adds, " but there are many forms
of these dots." It is also remarked that " exquisitely small and
black dots can often be seen in focal planes elevated slightly
above diatomic beads by using a black central stop below the
condenser. It requires very grand glasses to display these elegant
results." It is needless to point out that the late Dr. Royston-
Pigott was an upholder of the now abandoned view that the
perforations of diatoms were solid silex beads or bosses. The
foregoing sufficiently proves that the central eidolic dots or
" pores " of diatoms were well known twenty-six years ago, but
those specially interested in the subject should read the papers
referred to.
Setting aside all such diffraction phenomena, or false ghosts,
probably the most delicate, true diatomic structures just within
the grasp of our finest modern objectives of large aperture are
the thin perforated " veils "' to be detected on certain diatoms.
Of these perhaps one of the best examples is Triceratium america-
nitm, var., Oamaru, mounted in styrax by M oiler. It is a difficult
structure with axial screen illumination, but there can be little or
no doubt that the appearances observable represent real perfora-
tions in a thin outer plate. In this diatom there is no complicated
structure to bewilder the observer and manufacture false ghosts.
It is, however, extremely improbable that the minute perforations
of the IViceratium americanum, difficult as they are, represent
anything smaller than the 1/1 00,000th of an inch, and being
subject to the limitations of the laws of diffraction, like
all periodic structures, are consequently of little help as
an example of the minimum visible under more favourable
conditions.
A. A. C. ELIOT MERLIN ON THE MINIMUM VISIBLE. 389
In biological investigations it is frequently required to view
widely scattered living particles, or germs, of various sizes down
to the most minute dot that can just be detected. When any
such particle is under observation nothing is easier than to
measure its dimensions accurately by the anti point method.
There is in my cabinet a section of fluor spar, given to me by
Mr. Traviss, which contains numerous liquid-filled cavities of
various sizes. In each cavity there is a rapidly moving bubble.
Some of these bubbles, under a 1/1 2th apochromat of 1*4KA.,
appear as mere trembling specks only just visible and within the
grip of the objective, and there are probably others too minute
to be seen at all. Selecting a bubble just visible under such
conditions when illuminated with a large axial cone and Gifford
screen, if we wish to ascertain its diameter we have only to refer
to Mr. Nelson's papers, "A Micrometric Correction for Minute
Objects," * and " The Influence of the Antipoint on the Micro-
scopic Image shown graphically." f These papers contain all
the necessary explanations and data, and we find from the
amended table in the latter paper that with a working aperture
of 1*4 and screen the minimum particle visible must have a
diameter of 0-00000265 (l/377,358th) in., or 0'0673 /x : the photo-
graphic limit being with similar aperture 0-00000209 (l/478,4:69th)
in., or 0'5031 /x.
Thus we can measure accurately the diameter of the smallest
particle or bubble visible with a given aperture. The accuracy
of the result depends on knowing exactly the N.A. employed at
extinction point, and this must in each case be found with an
accurate apertometer. It is advisable that the working aperture
should nearly equal the N.A. of the objective at the extinction
point, but it need not necessarily be quite full cone. When the
critical point is reached a very slight decrease of N.A. makes all
the difference between easy visibility and invisibility. Mr.
Nelson's first table " was computed by the formula
5-4686 \ W.A.
The numerical coefficient was determined from data found by the
* Journ. R.M.S., 1903, pp. 579-82.
t Ibid., 1904, pp. 269-71. See also " On the Measurement of Very-
Minute Microscopical Objects " {Journ. R.M.S., 1909, pp. 549-50).
390 A. A. C. ELIOT MERLIN ON THE MINIMUM VISIBLE
extinction of the image of a minute point by reducing the W.A.
to 0'165. The size of the point was measured by a wide-angled
oil-immersion, and a W.A. of 0*9, and was found to be apparently
1/50, 050th inch. From this we have
6-6961X-165 = 50,050.
And
:0-000003663.
li-6961\-9
Employing this as a provisional correction, we find the size of the
point to be 1/4 2,396th in. Again, using this measurement, we
obtain a new numerical coefficient, viz. 5*6587, and finally find
the size of the point 1/40, 875th in., and the coefficient 5*4686 as
stated above. In this calculation A is the reciprocal of the wave-
length, or the number of waves per inch, given at the head of
each column in the table." In Mr. Nelson's subsequent paper,
" The Influence of the Antipoint on the Microscopical Image
shown graphically," the data will be found for the slightly
amended table given therein.
Shortly after the publication of Mr. Nelson's papers on this
interesting subject, Dr. Coles kindly sent me a well-stained
balsamed slide of the putrefactive microbe B. termo. On this I
was able to find a distinctly flagellated specimen suitable for
measurement by the extinction method. The flagellum could be
plainly seen with an apochromatic l/6th of 0*98 N.A. used with
a full cone and screen, and it became invisible when the N.A.
was gradually cut down to 0*42 by means of an iris diaphragm
over the top lens of the objective, thus making the diameter of
the flagellum 0*00000S91 (1/1 1 2,200th) in., or 0*226 fx.
Afterwards a balsamed-stained, flagellated specimen of the
tubercle bacillus was found. This was more difficult to see, and
the flagellum was thought to be much finer than that of the
B. termo. A 1/8 tli apochromat of 1*4 N.A. was employed to
measure this. When the N.A. was cut down to the vanishing
point and tested with the Abbe apertometer, it was found to bv
exactly 0*42, thus making the diameter of the tubercle bacillus
flagellum precisely equal to that of the B. termo. It may here
be mentioned that the existence of the tubercle bacillus flagellum,
discovered by Mr. Nelson, has been denied. It has, however,
A. A C. ELIOT MERLIN ON THE MINIMUM VISIBLE. 391
been observed by many microscopists, including myself, and has
been beautifully photographed by Mr. Nelson.*
Now the flagellum of B. termo was most carefully measured
by the late Dr. Dallinger, and his results were embodied
in a paper entitled " On the Measurement of the Diameter
of the Flagella of Bacterium termo : a Contribution to the
Question of the ' Ultimate Limit of Vision ' with our Present
Lenses." f Two hundred measurements were made by means of
a fine pencil mark made over half or two-thirds, not over the
whole, of the camera-lucida image of the flagellum. The labour
entailed may be judged from Dr. Dallinger's statement: "Now
I made fifty separate drawings and measurements with each
of the four lenses, the same conditions being observed in each
case. The results expressed in decimal fractions are as follows,
viz. :
" 1. The mean value of fifty measurements made with the
1/1 2th in. objective gives for the diameter of the flagellum
000000489208.
" 2. The mean value of fifty measurements made with the
l/16th in. objective gives 0-00000488673.
" 3. The mean value of fifty measurements made with the
l/25th in. objective gives 0-00000488024.
" 4. The mean value of fifty measurements made with the
l/35th in. objective gives 0-00000488200.
" We thus obtain a mean from the whole four sets of measure-
ments, which gives for the value of the diameter of the flagellum
of B. termo 0*00000488526, which, expressed in vulgar fractions,
is equivalent to 1 /204700th of an inch nearly; that is to say.
within a wholly inappreciable quantity."
These classical measurements of the diameter of the B. termo
flagellum are of the greatest importance, for by their means the
accuracy of the extinction method is demonstrated, which in turn
serves to confirm the exactness of the late Dr. Dallinger's results.
Assuming that a W.A. of 0 8 was employed, the necessary anti-
point correction by Mr. Nelson's amended table is 0*000005 13th in.,
which,addedtoDr.Dallinger'smean,makes0*00001001(l/99,900th)
in. for the true diameter of the flagellum, as against 0*00000891
* Journ. Q.M.C., Ser. 2, Vol. XI. PI. 22.
f Ibid., 1878, pp. 109-75.
392 A. A. C. ELIOT MERLIN ON THE MINIMUM VISIBLE.
(1/1 12,200th) in., the diameter obtained by me from Dr. Coles's
specimen by extinction measurement. The latter method is
certainly not second to Dr. Dallinger's in exactness, whileit is
undoubtedly less laborious. Through no fault of his own, Dr.
Dallinger's uncorrected figures put the diameter of the flagellum
at half its true dimensions.
Journ. Quekett Microtcopical Club, Ser. 2, Vol. XII., No. 75, November 1014.
39:;
REMARKS ON TWO SPECIES OF AFRICAN VOLVOX.
By Charles F. Eousselet, F.R.M.S.
(Read October 21th, 1914.)
The slides of two species of African Volvox which I am
exhibiting to-night have a history of unusual interest.
It will be remembered that at the meeting of this Club on
October 25th, 1910, a paper was read by Prof. G. S. West of
Birmingham University, in which two new species of Volvox
from Africa were described.
One of these, Volvox africames, of small size and oblong in
shape, was found in a Plancton collection made in July 1907
by Mr. R. T. Leiper, of the Egyptian Government Survey, near
the northern shores of the Albert Nyanza. I received a very
small quantity of this collection for the purpose of determining
the Rotifera it contained, and found these pretty oval colonies of
Yolvox, as did also Prof. West, who had received a similar
sample, in order to name the various fresh-water algae
contained therein.
The other species is of very much larger size (as much as
l/20th inch in diam.), of spherical shape and densely crowded with
cells on its surface (estimated at 50,000 cells in one of the larger
Colonies), was found by myself on the occasion of the visit of the
British Association to South Africa in September 1905 at
Gwaai Station in Rhodesia, about half-way between Bulawayo
and the Victoria Falls of the Zambesi ; the train stopped for
half an hour at this station by the side of a shallow pool formed
by the Gwaai River, and as usual I jumped out of the train with
my collecting- net and bottle and secured a dip from the pool.
As the train went on I examined the contents of my bottle, and
besides various Rotifera I noticed some large colonies of Volvox.
The whole collection was put up in formalin, and eventually the
specimens of Volvox were handed over to Prof. West for
description, which was done in our Journal in November 1910.*
Of both these African Species of Volvox vegetative colonies
only had been found, and Prof. West expressed his regret that
the sexual colonies in various stages were not represented, so
that his description was necessarily incomplete.
This closed the first stage of the story.
In May 1912 Dr. A. W. Jakubski published in the Zoologischer
Anzeiger a paper on Rotifera collected by him in the Ussangu
Desert in German East Africa, in which several new species of
Distyla were figured and described. At that time Mr. James
Murray was writing papers on the Rotifera of Australasia and
South America and in particular was studying the family of the
* Journ. Q.M.C., Ser. 2, Vol. XL, p. 99-104.
O
94 C. F. ROUSSELET ON TWO SPECIES OF AFRICAN VOLVOX.
Cathypnidae, and we considered it very desirable to obtain,
if possible, specimens of the new species described. So after I
had ascertained that the author was working at the Zoological
Institute at Lemberg University I wrote to Dr. Jakubski
asking him to be good enough to send me a little of the material
containing the species of Rotifera. Some time in the spring of
1913 the Doctor very kindly sent a few slides and also about eigh-
teen tubes of Plancton material collected in German East Africa.
By this time Mr. James Murray had left England on his way to
the disastrous North Canadian Arctic Expedition, from which
he has not returned, and being myself much occupied with other
work, 1 delayed the examination of this material until the spring
of the present year, when I received a polite reminder from the
sender asking for the return of his tubes as soon as convenient.
This request obliged me to look over the contents of the tubes
without further delay, which was clone in May and June last.
In his paper the author states that in deserts of German
East Africa pools and ponds are rare and can only be found after
heavy rainfalls, and are then shallow and last a very few weeks
only, but often develop a considerable amount of Plancton
organisms.
In two of the tubes, amongst various Rotifera, I was surprised
and fortunate to come across numerous colonies of Vol vox
which I at once recognised as the same two species from
Africa described by Prof. West four years previously. Moreover
both species were present in various sexual stages with
androgonidia and oospores, the male and female colonies, as
well as the vegetative colonies.* The ripe star-shaped oospores
of the large Volvox Rousseleti in particular are very fine and
remarkable, and these specimens will now enable Prof. West
to describe the complete life- history of both these African species,
which appear to be widely distributed in that continent, though
not as yet known from any other part of the world.
After completing my examination of the material I returned
all the tubes to Dr. Jakubski at Lemberg in Galicia early in
July, but have not heard whether they reached him. The
tragedy of the situation is that at the end of the same month
war was declared and Lemberg (Lwow) was one of the first
towns of importance taken and occupied by the Russian army,
and it is at present impossible to ascertain what has become of
either my correspondent or his collection of specimens.
You will agree that it was a piece of extraordinary and
remarkable good luck that these collections came into my hands
and at this particular time.
* Slides were exhibited by Mr. Eousselet showing the various sexual
stages.
Joum. Quekctt Microscopical Club, Her. 2, Vol. XII. , No. 75, November 1914.
395
REPORT ON THE CONFERENCE OF DELEGATES OF
CORRESPONDING SOCIETIES (BRITISH ASSOCI-
ATION) HELD AT HAVRE, 1914, BY INVITATION OF
THE ASSOCIATION FRANCAISE POUR L'AVANCE-
MENT DES SCIENCES.
{Bead October 27th, 1914.)
To the President and Council of the Quehett Microscopical
Club, London.
As your Delegate I attended the Havre Congress of the
French Association, which began on Monday, July 27th. The
Opening Meeting was held in the Grand Theatre, where Monsieur
Armand Gautier, the President, welcomed the members and
delivered an address. On behalf of the English members
Sir William Ramsay addressed the meeting in French. In the
evening there was a reception by the Mayor and Corporation
in the Town Hall. On the Tuesday I attended a Conference
of the Delegates of Corresponding Societies in the Town Hall,
when Sir E. Brabrook read a discourse on behalf of the Chair-
man, Sir H. G. Fordham, who was absent, " On the History
of British Association Conferences of the Delegates," of which
it appears Mr. John Hopkinson was the founder. Mr. Hop-
kinson read a paper on "Local Natural History Societies and
their Publications," in which he advocates certain rules in
the publication of Transactions which would render them more
easily capable of being referred to and quoted by inquirers
or the bibliographer, and at the same time save expense in
making reprints for distribution by the authors.
Sectional Meetings took place on the Tuesday and Wednesday,
although clouds were then gathering on the political horizon, and
some presidents of Sections did not appear. On the Thursday,
July 30th, the Congress went on an excursion by train and
boat up the River Seine as far as Rouen, visiting many historical
places of interest and some famous old and ruined cathedrals
and ancient Roman settlements, such as Lillebonne, Caudebec,
Jumieges, La Bouille, on the way.
On the following day, Friday, more meetings of Sections wTere
Journ. Q. M. C., Series II.— No. 75. 28
396 REPORT ON THE CONFERENCE OF DELEGATES HELD AT HAVRE.
held, but were very poorly attended, as the political outlook was
more and more threatening and many members were called away
and left hurriedly.
On Saturday, August 1st, most presidents and secretaries of
Sections had gone and only a very few meetings took place. On
that morning at the Zoological Section I read a short paper
in French on " Pedalion or Pedalia, a Question of Nomenclature
in the Class Potifera." About midday a Government announce-
ment or " Decret " was placarded at the Town Hall and at
Post Offices ordering a general mobilisation of the French Army,,
to commence at midnight, when the Congress broke up.
I left Havre the same night by steamer for Southampton r
where I arrived on Sunday morning, about three hours late, the
boat having been held up several times in the Channel by
torpedo-boats. Thus ended a most tragic meeting of a Congress
for the Advancement of Science.
(Signed) Charles F. Pousselet.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 75, November 1914.
o\n
PEDALION OU PEDALIA; UNE QUESTION DE
NOMENCLATURE DANS LA CLASSE DES ROTIFERES.
Par Charles F. Rousselet.
[Paper read by the author as the Queliett Club'' a Delegate to the Conference
of Delegates of Corresponding Societies of the British Association held at
Havre by invitation of the Association Franqaise pour V Avancement des
Sciences. Section de Zoologic, Seance du ler A out 1914.]
Au 6me Congres de l'Association Frangaise pour l'Avancenient
des Sciences term au Havre en 18"7 M. Jules Barrois presenta
un memoire portant le titre: "Sur 1'anatomie et le developpement
du Pedalia mira." (Seance de la Section de Zoologie du30Aoiit
1877.)
Or en 1871 le Dr. C. T. Hudson avait decouvert dans une mare
d'eau douce a Clifton pres de Bristol un Kotifere extraordinaire,
ayant six membres arthropodiques, l'un sur la face ventrale, un
second sur la dorsale, et deux de chaque cote du corps, au moyen
desquels 1'aniinal peut nager et avance dans l'eau par petits
sauts, semblables aux mouveruents des larves des crustaces
Cyclops. Hudson noinma l'animal Pedalion mirum.
En examinant ces jours le volume des Comptes rendus du
Congres de 1877 j'y trouve a la page 661 un Extrait de la com-
munication de Barrois portant le titre ci-dessus. On voit que le
nom de Pedalion a ete change en celui de Pedalia. En lisant
plus loin on y trouve les phrases suivantes :
" M. J. Barrois a ete conduit par ses etudes sur les Bryozoaires
a considerer la forme primitive de ces animaux comme comparable
a l'etat adulte des Botiferes. Pour elucider cette question
M. Barrois a entrepris au laboratoire de Wimereux l'etude de
l'embryogenie du genre Pedalion si interessant par la diversity de
ses organes appendiculaires et dont une espece est assez commune
a Wimereux. Ce Pedalion est une espece marine. II presente,
outre les deux epaulettes ciliees, six lambeaux d'epithelium
ciliaire qui forment par leur reunion une couronne presque com-
plete; les organes appendiculaires de la face orale sont au nombre
de six : quatre pointes chitineuses et deux boutons a cils raides ;
les points oculiformes sont au nombre de trois, dont deux
appartiennent a la face orale."
On voit que le nom de Pedalion est mentionne deux fois dans
cet extrait, tandis que celui de Pedalia n'y est pas nomme du
tout, ni y trouve-t-on une raison quelconque pour ce changement
de nom, qui se trouve uniquement dans le titre du memoire de
M. Barrois.
398 C. F. ROUSSELET ON PEDALION OU PEDALTA.
La question done s'impose : qui a ecrit ce titre ? est-ce
M. Barrois, ou le redacteur des Comptes rendus du Congres ?
J'ignore si le memoire de Barrois a ete publie en entier quelque
part, et je serai bien content d'en etre informe. La Revue
Scientifique du temps (No. 13, du 29. Sept. 1877) a publie le
merne extrait, sans le titre cepenclant, et par consequent le mot
Pedalia n'y est pas mentionne, mais seulement celui de Pedalion
a deux fois.
II y a autre chose encore : par la description que donne Barrois
il ressort bien clairement que son Botifere n'etait pas Pedalion,
qui ne vit pas dans la mer, n'a que deux yeux, n'a pas d'epaulettes
ciliees, ni de couronne ciliee en six lambeaux, ni six organes
append icul aires sur la face orale. Toute cette description
s'applique parfaitement a tine espece marine du genre Syncbaeta
(probablement S. triophthalma Lauterborn, qui porte ses ceufs
suspendus a la pointe de son pied en nageant), mais pas du tout
au Pedalion mirum de Hudson, qu'on rencontre un peu partout
en ete dans des mares d'eau douce.
II existe deux autres especes de Pedalion (P. fennicum Levander
et 7-*. oxyure Sernow) qui se trouvent tous deux dans les eaux
saum aires en Asie, en Egypte, en Amerique et en Australie,
mais aucune espece n'a encore ete decouverte en mer.
Par suite de 1'application des regies internationales de nomen-
clature le nom du genre Pedalion doit tomber, ce nom ayant ete
applique precedemment a un poisson (Swainson 1832), et a un
mollusque (Solier 1847).
II est done utile et necessaire de rechercher qui a le premier
employe le nom de Pedalia, et j'invite les membres de la Section
de Zoologie de bien vouloir me communiquer le memoire complet
de M. Jules Barrois s'il existe, ou toute autre information qui
pourrait elucider cette question.
Je ne parle pas de l'Hexarthra de Schmarda, qui pourrait
tres bien etre une espece encore plus ancienne de Pedalion ; e'est
une autre question que j'espere pouvoir resoudre sous peu, apres
m'avoir procure des peches dans le meme marais d'eau saumatre
a El Kab en Egypte oil Schmarda a decouvert son Hexarthra en
Mars 1853.
II resulte de cet expose que M. Jules Barrois (ou peut-etre
quelqu'autre personne) a non seulement change le nom de
Pedalion en celui de Pedalia, mais encore l'a applique a un
Svnchaeta.
Joarn. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 75, Koccmbc,- 1914.
399
THE LIBRARY.
BOOKS PURCHASED SINCE JANUARY 1914.
Optical Convention. Vol. II. 1912.
Sylloge Algarum Omnium. Vol. II. Sect. II. J. Bapt.
De Toni, 1892.
Bacteriological Examination of Food and Water. Wm.
G. Savage, B.Sc, M.D., D.P.H., 1911
BOOKS AND PHOTOGRAPHS PRESENTED SINCE
JANUARY 1914.
Revue Suisse de Zoologie a propos de Rotiferes. Vol. XXII.
No. 1. January 1914. E. Penard.
Presented by the Author.
Sylloge Algarum Omnium. Vol. II. Sect. I. Raphideae.
J. Bapt. De Toni.
Presented by the Author.
My Sayings and Doings. Rev. Win. Quekett.
Presented by G. W. Watt.
Cothurindes Muscicoles. E. Penard.
Presented by the Author.
Sur quelques Teulaculiferes Muscicoles. E. Penard.
Un curieux Infusoire, Lbgendrea bellerophon. E. Penard.
Presented by the A uthor.
Eighty Photographs of Drawings of Rotifera. By F. R.
Dixon -Nuttall.
Presented by F. R. Dixon-Nuttall.
Eighty Photographs of Rotifera.
Presented by J. B. Groom.
Royal Society of Victoria : Further Notes on Australian
Hydroids. Part II. W. M. Bale, F.R.M.S.
Presented by the Author.
400 THE LIBRARY.
< )donaten-Studien. C. Weseriberg-Lund.
Presented by the Author.
WOHNUNGEN UND GEHAUSEBAU DER StJSSWASSERINSEKTEN. C.
Wesenberg- Lund.
Presented by the Author.
FoRTPFLANZUNGSVERHALTNISSE PAARUNG UND ElABLAGE DER
Susswasserinsekten. C. Wesenberg-Lund.
Presented by the Author.
Commonwealth of Australia, Department of Trade and
Customs : Fisheries. Biological Results of Fishing Ex-
periments carried on by T.I.S. Endeavour. 1909-14.
Report on the Hydroida Collected in the Great Australian
Bight and other Localities. W. M. Bale, F.R.M.S.
Presented by the Author.
The Journal of Micrology. Parts I. -IV.
Presented by H. Edwards.
For Sale — 50 copies — reprints of Paper " Lagenae of the
South- West Pacific Ocean," by Henry Sidebottom. Two Parts.
Price 2s. Gd. Application should be made to the Librarian.
401
THE CLUB CABINET.
The following Slides have been added to the Cabinet since
October 1912 :
Protozoa.
Presented by G. T. Harris.
K.A. 106. Actinosphaerium Eichomi (binary fission).
Infusoria.
Presented by J. C. Kaufmann.
K.A. 102. Euglena sp.
Presented by J. Burton.
107. Euglena viridis.
Presented by G. T. Harris.
103. Ephelota sp. (stained to show nucleus).
104. Ephelota sp.
105. Noctiluca miliar is.
Hydrozoa.
Presented by G. T. Harris.
(s = stained.)
M.A. 4:. Aglaophenia pluma, s.
50. Aglaophenia pluma (gonophores).
51. Bougainvillia, muscus.
14. Cah/cella syringa.
23. C ampamdaria Jlexuosa, s.
52 . C ampamdaria flexuosa.
53. C ampamdaria neglecta.
54. Clara carnea.
402 TJ1E CLUB CABINET.
M.A. 55. Clava carnea, s.
56. Clava midticornis, s.
57. Clava squamata, s
17. Clytia Johnstoni, s.
58. Clytia Johnstoni.
91. Clytia Johnstoni (medusa).
19. Cordylophora lacustris, s.
59. Cordylophora lacustris (with compound bud), s.
8. Coryne pus ilia, s.
60. Coryne vaginata (gonophores), s.
61. Coryne vaginata [with epiphytal Licmophora /label -
lata).
62. Coryne vaginata, s.
63. Eudendrium insigne,
64. Eudendrium insigne [with Ephelota : Infusorian).
65. Gonothyrea Loveni.
66. Halecium Bcanii.
67. Hydra fusca.
68. Hydra viridis (ovary and testes), s.
69. Hydra vulgaris, s.
92. Lizzia Blondini (medusa).
93. Lucernaria fascicularis (medusa).
70. Obelia dichotoma, s.
71. Obelia dichotoma.
72. Obelia geniculata, s.
73. Obelia geniculata.
74. Perigonimus sessilis.
75. Plumularia echinulata.
76. Plumularia echinulata.
77. Plumularia echinulata, s.
78. Plumularia echinulata, s.
79. Plumularia halecoides, s.
80. Plamidaria halecoides.
81. Plumidaria pinnata.
82. Plumularia setacea.
83. Plumidaria setacea.
84. Plumularia setacea (metatophores).
85. Plumularia siinilis, s.
86. Plumularia similis.
87. Podocoryne areolata, s.
THE CLUB CABINET. 403
M.A. 28. Sertularia frfiada.
88. Sertularia pumila, s.
89. Sertularia pumila.
90. Serti'liiri'i pwmila.
Echinodermata.
Presented by J. Burton.
N. 19. Plates of Taeniogyrus A llani.
Rotifera.
Presented by J. C. Kaufmann.
Rot. 246. Lacinularia elliptica.
Turbellaria.
Presented by H. Whitehead.
Series 20 : v:ith descriptive notes and diagrams.
Jficrostomum lineare.
Phaenocora (Derostomum) punctatum.
Daly el Ha viridis.
Daly ell ia diadema.
Gyratrix herm aphrodit us.
Dendrocoelum lacteum.
Planaria alpina.
Planar ia alpina : tr. and long. sees.
Planaria gonocephala.
Polyeelis nigra.
Poly celis nigra : tr. sec.
Polyeelis cornuta.
V B. 35. Tr. sec. (serial) of a Planarian.
Insecta.
Presented by T. A. O'Doxohoe.
R. 402. Scales of Templetonia crystallina.
403. Scales of Seira Buskii.
Presented by F. H. jST. C. Kemp.
399. Xaucoris cimicoides (adult).
404 THE CLUB CABINET.
Polyzoa.
Presented by G. T. Harris.
M.B. 33. Aetea anguina.
84. Bowerbankia imbricata.
85. Pedicellina cernaa.
80. Pedicellina cemua, var. gracilis.
Physiological Histology.
Purchased. (With descriptive, illustrated text.)
Series 10. The Shin.
Human scalp, with hair : long, and tr. sees.
Human scalp, with hair : long, sec, injected.
Human skin, with perspiration glands : long. sec.
Human skin, stages of development of perspiration glands : long.
sec.
Human skin, with blood vessels injected : long. sec.
Skin of Dog, with elastic fibres : long. sec.
Tactile hairs of Ox, with blood sinus : tr. sec.
Human hair, stages of development : long. sec.
Human nail : lon^. sec.
*&■
Series 11. Muscle, bone, etc.
Human embryo, finger and arm : long. sees.
Muscle of Ring Snake, with motor nerve plates.
Muscle of Dog : tr. sec. and long, sec, injected.
Tendon of Ox : tr. sec.
Cervical ligament of Ox : sec.
Bone of Ox : long, sec
Cranial bone of Dog : sec.
Joint of Rabbit : median sec. ,
Series 12. Central nervous system.
Spinal cord and ganglion of Cat : tr. sec.
Spinal cord of Cat (Golgi preparation : cell impregnation).
Spinal cord of Dog : tr. sec.
Cerebral cortex of Cat (Golgi preparation : cell impregnation).
THE CLUB CABINET. 405
Cerebellum of Cat (fibre impregnation).
Cerebrum of Man (fibre impregnation).
Pineal gland of Ox : tr. sec.
Pituitary gland of Ox : tr. sec.
Embryonic spinal cord of Fowl.
Embryo of Rabbit : tr. sec.
Series 13. Reproductive organs.
Penis of Bull : tr. sec.
Glandula vesicularis of Bull : sec.
Spermatozoa of Bull.
Testis of Mouse : tr. sec.
Umbilical cord of Child : tr. sec.
Gravid uterus of Pig : tr. sec.
Oviduct and ovary of Dog : tr. sees.
Ovary of new-born Kitten : tr. sec.
Mammary gland of Cow : tr. sec.
Series 14. Respiratory and urinary organs.
Lung of Cat : injected.
Lung of Cat (elastic fibres).
Lung of Dog (cell pigmentation).
Trachea of Cat : tr. sec.
Kidney of Rabbit : injected.
Kidney of Mouse : tr. sec.
Bladder of Ox : tr. sec.
Supra-renal capsule of Ox : tr. sec.
Embryonic okenian body of Pig : tr. sec.
Thyroid gland of Man.
Series 15. Tic Eye.
Cornea of Ox (gold impregnation).
Choroid of Ox, showing pigment cells.
Retina of Ox.
Optic nerve of Ox : med. sec.
Eyelid of Calf : med. sec.
Lachrymal gland of Ox.
Glands of nictitating membrane of Rabbit.
406 THE CLUB CABINET.
Anterior half eye of Ox, without lens : hor. sec.
Eye of embryo Chick : med. sec.
Eye of embryo Pig : med. sec.
Series 16. Organs of hearing, smell and touch.
Auditory organ of Cat (sensory hairs of ampullae).
Auditory organ of Cat, membrana tympani : tr. sec.
Auditory vesicle of embryo Rabbit : long. sec.
Cochlea of Guinea Pig : med. sec.
Nasal mucous membrane of Cat : tr. sec.
Nasal mucous membrane of Rabbit, respiratory portion.
Olfactory mucous membrane of Rabbit : tr. sec.
Circum vallate papillae of Ox : mecl. sec.
Papilla f oliata of Rabbit : tr. sec.
Pacinian corpuscles in human skin.
Series 17. Circulatory and blood-forming organs.
Renal artery and vein of Pig : tr. sec. (fibres stained).
Renal artery and vein of Pig : tr. sec. (cells stained).
Human muscle of heart : tr. sec.
Embryo of Rabbit : tr. sec. in region of heart.
Human blood : film preparation.
Human blood : haemin crystals.
Red bone marrow of Pig.
Human spleen : sec.
Human thymus gland (child) : sec.
Lymphatic gland of Pig : sec.
Presented by C. L. Curties.
(Slides remounted by the late Sir Benjamin Ward Richardson
over 50 years ago.)
X. 428. Medulla of Cat : tr. sec, injected.
429. Tongue of Rat : tr. sec, injected.
430. Duodenum of Turtle : tr. sec.
431. Intestine of Guinea Pig : vert, sec, injected.
432. Jejunum of Cat : vert, sec, injected.
433. Large intestine of Pig : tr. sec, injected.
434. Retina of Rat : injected.
435. Toe of Mouse : long, sec, injected.
THE CLUB CABINET. 407
X. 436. Human tooth : tr. sec.
437. Human large intestine : vert, sec, injected.
438. Human jejunum : vert, sec, injected.
440. Human sole of foot : vert. sec.
Freshwater Algae.
Presented by J. Burton.
B. 112. Anabaena circinalis.
122. Apiocystis Brauniana.
119. Batrachospermum moniliforme.
114. Bulbochaete sp.
117. Chaetophora incrassata.
116. Choaspis stictica.
(Chrobcoccics turgid us.
' {0 oelosphaerium Kuetzingianum.
115. Cladophora flavescens.
127. Cladophora sp. (Lake Zurich).
B. 121. Clathrocystis aeruginosa.
123. Coleochaete scutata.
125. Cosmarium nitidulum.
( Cylindrospermum stagnate.
' {Lyngbya sp.
125. Jlerismopedia sp.
41. Micrasterias rotata.
128. Oscillator ia princeps.
113. Pandorina morum.
129. Sphaeroplea annulina.
118. Spirogyra sp.
120. Tolypothrix la/iata.
130. Trichodesmium Ehrenbergi (Atlantic Ocean).
53. Zygnema sp.
Presented by Exor. of J. M. Allen.
B. 111. Ballia pulchrinum.
Diatomaceae.
Presented by S. E. Akehurst.
A. 690. Amphipleura pellucida (realgar).
408 THE CLUB CABINET.
Presented by J. Burton.
A. 688. Rhipodophora meneghiniana, on Ectocarpus.
689. Achnanthes sp., conjugating on Marine Algae.
Purchased : mounted in styrax.
A . 691. A ctin ocyclus pruinosus.
692. Actinoptychus Bismarckii.
693. Actinoptychus Grunowii.
694. Actinoptychus hexagonus.
695. Actinoptychus maculatus.
696. Amphora Grevillei.
697. Asterolampra aemulans.
698. Auliscus mirabilis.
699. A uliscus permagna.
701. Biddulphia Roperiana (showing mode of growth).
702. Biddulphia Tuomeyi.
700. Brebissonia Weissjlogii.
703. Campylodiscus stellatus.
704. Clyphodesmis Challenger ensis.
705. Cocconeis extravagans.
706. Diploneis exemeta.
707. Kntogonia Daveyani.
708. Gymatopleura solea.
709. Hantzschia marina.
710. Mastogloia cruciata.
712. Navicula carinifera.
711. Navicula follis.
713. Navicula gemmulatula.
714. Navicula irrorata.
715. Navicula luxuriosa.
716. Navicida notabilis.
717. Nitzschia scalaris.
718. Omphalopsis australis.
719. Opephora Schivartzii.
720. Pinnularia dactylis.
721. Plagiogramma validum.
252. Pleurosigma balticum.
722. Podocyrtis adriaticus.
723. Raphoneis (uujjhi.ceros.
THE CLUB CABINET. 40!)
A. 724. Stephanopyxis Campeachiana.
725. Stictodiscus Nova- Zealand ic us.
72G. Stictodiscus par ellel us, var. gibbosa.
727. Surirella lata, var. robusta.
728. Surirella Macraeana.
729. Terpsinoe americana.
730. Triceratum dejinitum.
731. Triceratum favus, var. quadrata.
732. Triceratum favus, var. maxima.
733. Triceratum fractum.
734. Triceratum grande.
735. Triceratum Nova-Zealandicus.
736. Triceratum Robertsianum.
Fungi.
Presented by J. Burton.
C. 190. Sphoeria herbarum.
191. Sphoerella rusci.
Bacteria.
Presented by J. Burton.
0. 140. Cohnia roseo-persiciaa.
Plant Structure.
Presented by C. J. H. Sidwell.
E. 38. Leaf of Hydrocharis morsus-ranae\ ri tl n
q~t * *™ j ,- • •• -Cellular structure,
of. Leai oi lradescantia virginica J
E.A. 55. Leaf of Croton zambesicus
58. Leaf of Cynoglossum micranthum
52. Leaf of Onosma alboroseum
57. Leaf of Onosma stellulatum
53. Leaf of Onosmodium carolinianum
24. Leaf of Rhododendron Dalhousia
56. Leaf of Rhododendron Maddeni
51. leaf of Trirhodpsma indicum
54. Leaf of Trichodesma khasiana
Hairs and
glands.
410 THE CLUB CABINET.
Seeds.
Presented by C. J. H. Sidwell,
G. 43. Anagallis arvensis.
41. Castilleja sp.
46. Castilleja Cidbertsoni.
43. Cerastium glomeratum.
39. Delphinium niacrocentron.
47. Linaria vulgaris.
42. Mohavea viscida.
45. Pedicular is Frederica-Augusti.
44. Picrorhiza Kurrooa.
40. Tricholoena rosea.
ill
PROCEEDINGS
OP THE
QUEKETT MICROSCOPICAL CLUB.
At the 497th ordinary meeting of the Club, held on March 24th,
1914, the President, Prof. A. Dendy, D.Sc, F.R.S., in the chair,
the minutes of the meeting held on February 24th were read and
confirmed.
Messrs. C. W. Engelhardt, Harry Albert St. George, E.
Hermann Anthes, Felix R. W. Brand, Victor M. E. Koch,
Francis W. Lloyd, Leonard R. Gingell and His Excellency
Nicholas Yermoloff, K.C.Y.O., were balloted for and duly elected
members of the Club.
*
The list of donations to the Club was read, and the thanks of
the members voted to the donors.
The President said : " My attention has been called to the
fact that Mr. Powell, one of our oldest and best-known members,
is present this evening. I am also informed that Mr. Powell
celebrated his eightieth birthday on Saturday last. May I be
allowed, on behalf of the Club, to offer him our sincere con-
gratulations on this occasion, and to express our satisfaction that
he is still able to be present at our meetings ? "
Mr. J. W. Ogilvy (Messrs. Leitz) exhibited an illuminator for
opaque objects which consists of a bull's-eye and a stage-condenser
fitted to a bar which is carried on a stand having universal
movements. Being in one piece, time is saved in setting up the
apparatus.
Mr. N. E. Brown, A.L.S., read " Some Notes on the Structure
of Diatoms."
An animated discussion followed the paper, in which the
President and Messrs. O'Donohoe and Ainslie took part, and to
which Mr. Brown replied.
A hearty vote of thanks was given to Mr. Brown for his
interesting paper.
The Hon. Sec. read a paper, communicated by Mr. E. M.
Nelson, F.R.M.S., on " A New Object-glass by Zeiss, and a New
Method of Illumination."
Journ Q. M. C, Series II.— No. 75. 29
412 PROCEEDINGS OF THE
Messrs. Zeiss exhibited the new oil-immersion l/7th on four
microscopes, and the thanks of the meeting were accorded to
Messrs. Zeiss and to M. Koch, who represented the firm.
At the 498th ordinary meeting of the Club, held on April 28th,
1914, the Vice-President, Mr. D. J. Scourfield, F.Z.S.,F.R.M.S.,
in the chair, the minutes of the meeting held on March 24th
were read and confirmed.
Messrs. Edward Carlile, Francis Cooley-Martin, Gerald Burton
Burton-Brown, M.D., Francis Edward Robotham and Daniel
Arthur Davies, jun., were balloted for and duly elected members
of the Club.
The list of donations to the Club was read and the thanks of
the members voted to the donors.
The Hon. Sec. read a note on " A New Low-power Con-
denser," communicated by Mr. E. M. Nelson, F.B..M.S.
Mr. C. Lees Curties (Messrs. C. Baker) exhibited both the
low -power condenser designed by Mr. Nelson and also a simple
centring-stop holder which he had suggested.
Replying to a question, Mr. C. Lees Curties said that the
aperture of the condenser was 0*55. On account of its long
working distance, the condenser would be particularly useful for
dark-ground illumination when examining pond-life in a
trough.
Mr. M. A. Ainslie said that the Leitz achromatic condenser
with the top off had an aperture of 0'6, and a working distance of
one-third of an inch. He would suggest that, when necessary,
the condenser should be decentred, in order to centre the stop.
He frequently did this with low powers, when necessary.
Votes of thanks to Mr. Nelson and to Mr. Curties were pro-
posed and carried unanimously.
Mr. N. E. Brown, A.L.S., gave an account — illustrated with
fresh specimens of the flower and a coloured drawing of a longi-
tudinal section — of " The Fertilisation of Vinca minor" He
said that a very interesting microscopic object was concealed in
this flower. As regards its fertilisation, a special interest was
connected with the flower of the periwinkle. The fruit of this
plant is extremely rare, not only in this country, but also on the
Continent. The flower has a. very remarkable structure, and a
QUEKETT MICROSCOPICAL CLUB. 413
section exhibiting the stigma has several points of interest. At
the bottom of the tube are two large glands which secrete honey,
one on each side of the ovary. The ovary has two carpels, which
are separate, but are united at the top into a single style. This
goes up, and at the top expands into a wing-like disc, and termi-
nates with a crown of hairs like a sweep's brush. Some of these
hairs turn down into five little tufts, forming little alcoves, which
play very important functions. From the corolla arise five
stamens. The anthers are raised above, and are so curved over as
to enclose the whole and prevent ingress except between each pair
of stamens. The anthers open while in the bud, and then shed
their pollen, which, when the flower opens, is seen to be deposited
in five little heaps. Underneath the wheel-like formation, often
spoken of as a stigma, we find a frill-like, orange-coloured body,
which is not of the same depth all round, but opposite the little
alcoves already referred to deepens slightly. The true stigma is
formed by this curtain, or frill, and there we find the true stig-
matic tissue. Now as regards fertilisation. Insects (bees) come
for the nectar situated at the base. Grooves guide the tongue
between two anthers and past the upper ledge of the shelf, or
frill. Here it passes the little masses of pollen, which are slightly
glutinous, and, before reaching the honey-glands, comes in contact
with a wet, viscid fluid. ^Yhell the tongue is withdrawn, the
smeared surface comes in contact with the mass of pollen, which
adheres to it. But the plant does not want to part with all its
masses of pollen, and so some is scraped off the proboscis by the
projecting hairs, and remains until the visit of another bee,
which, perhaps, has already visited a periwinkle flower. The
tongue passes down past the stigmatic frill ; but in coming back
scrapes the pollen off on the under side, no trace of pollen
remaining on the part of the tongue previously smeared with
the viscid matter. This is the manner in which the plant is
fertilised. Last year the speaker had examined many plants in
order to see if they had been fertilised. It is commonly stated
that V. minor is infertile to its own pollen, and so seeds are rare.
Nearly all plants in one locality are probably products of one
plant, and have not come from seed. Of the plants examined,
70 per cent, had been fertilised by insects ; but no fruit of any
kind developed on the clump under observation. Mr. Brown this
year had fertilised one hundred flowers ; but it is yet too early to
414 PROCEEDINGS OF THE
be able to report any results. This year was noticeable for a
great dearth of pollen, all the anthers being more or less barren.
He awaited with interest the result of his artificial pollination.
The Chairman said that at first thought it might possibly be a
case of over -elaboration.
Mr. R. Paulson asked if Mr. Brown had cut sections to see if
any of the pollen grains had thrown out tubes. He preferred to
distinguish between the terms " pollination " and " fertilisation."
As is well known, there are some plants in the British flora
where pollination does take place, but which are infertile. As
an instance he would mention the lesser celandine Ranunculus
fizaria. Had Mr. Brown ever seen any seeds of this plant 1 It
might be imagined that its seeds would be very numerous ; but
this is not the case. It does seem that in many plants we have
instances of over-elaboration. He would instance orchids and
violets — and especially with regard to violets. Violets produce
abundant seed, not by the attractive flowers, but by little green
flowers which are usually missed by the ordinary observer.
These little green flowers never open and the anthers shed their
pollen directly on to the stigmas.
Mr. 0. E. Heath asked whether the pollen of Vinca minor had
been seen to form tubes.
The Hon. Secretary suggested that the pollen might be tested
practically, under the microscope, in a weak solution of sugar-
and-water. If the grains did put out tubes, he thought it would
prove the possibility of fertilisation.
Mr. Brown, replying, said that even if the pollen grains pro-
duced tubes in a sugar-and-water solution, it would be no
guarantee that they would also do so in the flower. He intended,
however, to examine the pollen and also to cut sections.
Regarding the celandine, in the South of England it seeds quite
freely. It is possibly a question of temperature. Not all violas
have cleistogamous flowers ; some usually produce seed from the
ordinary open flowers.
The Hon. Secretary (Mr. James Burton) read a note on "An
Abnormal Form of Arachnoidiscas ornatus." He wished to draw
attention to the plate of Arachnoidiscus, by Beck, in Carpenter's
The Microscope and its Revelations, a copy of which was on the
table. The drawing represented the diatoms entire and still
attached to the seaweed on which they occurred. It showed their
QUEKETT MICROSCOPICAL CLUB. 415
living form. That which we are accustomed to find on mounted
slides is only a part of the organism. He was exhibiting, under a
microscope, a slide given him by Mr. Williams, of Folkestone,
which displayed very beautifully the box-like form of this diatom.
It consists of a top and a bottom circular plate, known as valves,
to each of which is attached a ring, called by some authors the
girdle ; that of the top — or lid, as it might be called — fitting
outside that of the lower, or box -like, part. The whole closely
resembles an ordinary circular " chip '! specimen-box. On the
slide exhibited, examples of an abnormal form occur, in which
the bottom of the box has the "girdle" greatly elongated, the
"lid" still remaining shallow, as in a normal form. This struc-
ture gives the diatom, when viewed sideways, the appearance of a
cylinder, instead of that of a disc with but slight depth, and when
observed under a binocular with dark-ground illumination the
difference is very striking. The girdle is marked by circles of
lines running round, as though it were composed of superimposed
rings. On the rings are small projections or points. The
frustules are empty, and there is no appearance of the com-
mencement of dividing-walls inside, which might have indicated
that the unusual form was owing to the beginning of the process
of subdivision. In a normal form the depth was 30 /x ; in a case
where subdivision was far advanced the depth was 54 /x. In an
abnormal specimen the depth was 96 /x; another was 105 /x. The
diameter in all the forms measured is fairly constant, varying
from 105 /x to 114 /x. The abnormal form is only known to occur
in one collection of material from Mauritius, and in that the
percentage is very small. No explanation or suggested cause of
the unusual form was forthcoming.
Mr. Burton was complimented on the opportunity of bringing
this interesting slide under the notice of members.
Several members had interesting exhibits under microscopes,
Mr. G. K. Dunstall showing Flosadaria cyclops, which is worthy
of being recorded.
At the 499th ordinary meeting of the Club, held on May 26th,
1914, the President, Prof. A. Dendy, D.Sc, F.R.S., in the chair,
the minutes of the meeting held on April 28th were read and
confirmed.
Messrs. Henry Turing Peter, Sydney G. Bills and .Robert
416 PROCEEDINGS OF THE
William Buttemer were balloted for and duly elected members of
the Club.
The list of donations to the Club was read and the thanks of
the members voted to the donors.
Mr. W. R. Traviss exhibited a number of specimens of insects
in amber.
Mr. A. E. Hilton read " Some Notes on the Cultivation of
Plasmodia of Badhamia utricularis" He said that a free-
flowing mass of naked and almost undifferentiated protoplasm,
such as we have in a plasmodium of B. utricularis, suggests
opportunities for biological experiments with unusual promise of
success.
The chief purpose of this paper, Mr. Hilton said, was to place
on record the results of experiments made during the last few
months, which suggest a method of continuous cultivation of
plasmodia of B. utricularis at once simple and practicable.
The President said they were very much obliged to Mr. Hilton
for his very interesting and practical paper, which he should find
of great value to himself, as he had hitherto had great difficulty
in feeding this organism. He hoped the methods described would
come into general use for laboratory work, where the plasmodium
was very useful as an illustration. He should like to ask
Mr. Hilton if he had tried how long he could keep the plas-
modium in a dry state on the blotting-paper. Mr. J. J. Lister
at Cambridge used to feed it on fungus, but this was sometimes
difficult to get. He hoped that many members of the Club would
experiment in the manner suggested.
Replying to several questions, Mr. Hilton said the dried
sclerotium is capable of reviving after at least three years; but
it must be kept dry, and never allowed to become damp. After
so long a period, it might take four or five days to recover. He
could not say if it were possible to cultivate the plasmodium form
from sporangia. A difference in colour has been noticed in
specimens cultivated on plain bread compared with specimens
fed on the special mixture. The former are a lighter yellow
than the latter ; but various shades of yellow are present even in
one plasmodium. He had found a constant temperature of about
50° F. the best.
A very hearty vote of thanks was accorded to Mr. Hilton for
his paper.
QUEKETT MICROSCOPICAL CLUB. 417
The Hon. Secretary read a paper on " Binocular Microscopes,"
communicated by Mr. E. M. Nelson, F.R.M.S. In recent years
several binoculars have been introduced, none of which, however,
can be called new. The first, the Greenough, by Zeiss (Journal
R.M.S., 1897, pp. 599, 600), was a twin microscope — a form of
binocular invented by Pere Cherubin d'Orleans nearly three
hundred years ago. The second — by F. E. Ives, in 1902 {Journal
R.M.S., 1903, p. 85) — is very similar to one designed by Wenham
in 1866 as a counterblast to Powell's high-power binocular, in
which the whole beam is sent into each eye. The third, a modifi-
cation of the second, by Leitz {Journal R.M.S., 1914, p. 5), and
the fourth, by Beck, which is very similar to that of Ives.
Mr. Nelson concluded his paper by some remarks on the
position of the two new binoculars. From what has been said,
it will be seen that they are a class by themselves. It would be
quite inaccurate to entertain the idea that these instruments are
a new kind of stereoscopic binocular constructed to enter into
competition with, and finally to supersede, existing binoculars of
the Wenham and Stephenson type, for they only possess the first
attribute — stereoscopism — in a limited manner. Their use is
confined to the employment of full Ramsden discs in each eye —
that is, for work with non-stereoscopic images. When prolonged
work is undertaken with one of the new binoculars, great relief
and comfort to the eyes will be secured.
Messrs. Beck, represented by Mr. C. Beck and Mr. Creese,
exhibited two of their new model high-power binoculars, one
giving an excellent image of Pleurosigma angulation with a 1/1 2th
oil-immersion, and on the other stand a lower power exhibited to
perfection, first, stereoscopic, and, second, pseudo-stereoscopic
vision obtained by altering the tube-length. Mr. Creese also
exhibited a Wenham binocular with a l/6th objective, giving a
perfectly evenly illuminated field at 300 diameters of a section of
the eye of the drone-fly.
Messrs. Leitz's London representative, Mr. J. W. Ogilvy,
showed seven stands of their new model, with powers ranging
from 1/1 2th oil-immersion apochromat and 1,500 diameters to
1 in. and x 35. Two Leitz-Greenough models with low powers
were also exhibited. The preparations shown included Amphi-
pleura pellucida, Poclura scale, rock sections, and histological
preparations.
418 PROCEEDINGS OF THE
Mr. Nelson also sent for exhibition a photograph of a new
slide, designed by Mr. G. Nelson, for the portable Greenough, to
hold three pairs of objectives. It allows the powers to be changed
by moving the slide forward, and, in brief, is for the Greenough
what a rotating nosepiece is for an ordinary microscope.
At the 500th ordinary meeting of the Club, held on June 23rd,
1914, the Vice-President, Mr. E. J. Spitta, L.R.C.P., M.R.C.S.,
in the chair, the minutes of the meeting held on May 26th were
read and confirmed.
Messrs. Geoffrey Norman, Charles James Reeves King, William
Henry Scott, Charles Worthington Hawksley, Martin Herbert
Oldershaw and Edmund John Weston were balloted for and duly
elected members of the Club.
The list of donations to the Club was read and the thanks of
the members voted to the donors.
Mr. Watson Baker, jun., read a short paper describing a
series of sections of fossils from the Coal Measures. Many of
these were not only rare, but were almost unique in the beautiful
manner in which they showed the various structures, both of
plants and animals. They were exhibited under a number of
microscopes, lent and arranged for the occasion by Messrs.
Watson & Son. There were on view, also, whole specimens
still attached to the rock in which they were found. Mr. Watson
Baker said the specimens had been sent to him by a well-known
authority on palaeo-botany, and as many of them were of unusual
merit, he thought the Club would like to see them. He then
gave an interesting description in some detail : a condensed account
is as follows : No. 1. A specimen of the lower jaw of Elonicthys,
with teeth in situ. No. 2. Flank scales from the same. Elonic-
thys is a genus of fishes having a bony armour or a skeleton.
Devonian and Carboniferous, they existed in large numbers and
great variety, some attaining a great size. No. 3. A specimen of
the Caeleanthidae (hollow-spined fishes), which range from the
Upper Devonian to the Chalk. Specimens of these in situ were
on the table. Nos. 4 and 5 were sections of teeth of species of
shark, Diplodus equilateralis and D. gibbosus ; also an uncut
example of one of the teeth. Nos. 6 and 7. Sections of coal from
Mossfield Colliery, Longton, showing various vegetable tissues.
QUEKETT MICROSCOPICAL CLUB. 419
Microspores and Megaspores — reproductive organs resembling
those of modern Lycopods were clearly evident. No. 8. Plant
remains of a similar character. No. 9. A number of Fern
sporangia, showing the annulus, etc., embedded in a matrix of
fragmentary plant remains. No. 10. A section showing the
seeds of Cordaites : a genus of fossil-plants allied to some of the
recent Gymnosperms.
The chairman remarked on the very beautiful series of micro-
scopical slides, and on the hand specimens on the table, and pro-
posed a vote of thanks to Mr. Watson Baker, which was responded
to heartily.
The Hon. Secretary read a letter from Dr. M. C. Cooke, and
extracts from others received from Alphaeus Smith, Albert D.
Michael and G. 0. Karrop, who were unable to be present, con-
gratulating the Club on its continued prosperity, and wishing
it all success in the future. These were received with much
appreciation by the meeting.
The chairman then gave a short resume of the history of the
Club. He said that though named in honour of the celebrated
Dr. Quekett, it was not founded by him, originating four or five
years after his death. It was considered by a Mr. Gibson that
an association of amateur microscopists was desirable, and he put
an announcement into Hardwicke's Science Gossip to that effect.
The idea at first seemed to be to combine music and microscopy
at the evening meetings. The suggestion was rapidly and
enthusiastically taken up, and in July 1865 the Club was
definitelv started. Soon the meetings came to be held at
University College ; but it is curious to note that some of the
preliminary ones were held in Hanover Square, so that, again
occupying rooms in Hanover Square, the Club has returned to
its old locality. Among the very earliest members Mr. Lewis's
name appears. He was elected in April 1866 — forty-eight years
ago, and has held the position of honorary reporter from the
very early years of the Club. He has attended 485 out of
the 500 ordinary meetings — almost certainly a record — and
several of the omissions occurred only this last winter, owing
to illness and advancing years. Another very old member is
Mr. Alphaeus Smith, who held the post of hon. librarian
for forty years, and is still a member, though not on the active
list. Dr. M. C. Cooke, Mr. J. Terry, Mr. T. H. Powell, and
420 PROCEEDINGS OF THE
Mr. Millett all joined in 1865, and are still members. Dr.
Spitta referred to the work of Dr. Karop and Mr. Earland,
both of whom had been hon. secretaries in former years, and to
whom the Club was greatly indebted for its success. Lantern
photographs of Dr. Quekett and of pages of the old attendance-
books, showing names of original members, and various scenes
connected with the Club's life, were thrown on the screen.
Dr. Spitta wound up his interesting and delightfully humorous
discourse by recounting a supposed reverie (in verse) in which he
saw most of the present officers and prominent members coming
into a meeting, and detailed with delicate skill and good nature
their hobbies and characteristics. He then called upon some of
the older members—of whom a satisfactory number had been
able to attend — to say a few words.
Mr. Lewis made a little speech, in which he disclaimed the
title of "veteran," as he said Mr. Powell was before him, and he
spoke of Mr. A. Smith, who joined just after him. He was able
in some respects to supplement the chairman's remarks of what
took place at the earliest meetings, and said in conclusion that
" though my recent illness has shaken my health, and I shall
have to give up many things, the last I shall give up will be the
Quekett Microscopical Club, from which I have derived much
information, and have made many old and valued friends, and no
one connected with the Club has its interests more at heart than
myself." His remarks were received with enthusiasm by the
members, who showed their appreciation by prolonged cheers.
Mr. T. H. Powell (forty-nine years a member) wound up what he
said by remarking that he always enjoyed himself at the pleasant
meetings of the Quekett. Mr. F. Enock addressed the meeting
appropriately, and was followed by Mr. Earland, who made an
interesting and humorous speech on some of his experiences as
secretary. He, like others, referred to Mr. Lewis, and rejoiced
to see him still at the seat at the reporter's table he had occupied
so long. Again the audience showed their appreciation by cheers.
Mr. Hilton followed. He pointed out that till quite recent
years, during the long career of the Club, there had been only
two librarians, owing to Mr. Smith's long tenure of the office.
He also remarked on the large attendance at the meetings now,
saying that they could not realise what it was to have a meeting
with only six or even fewer present ; but stated that there was
QUEKETT MICROSCOPICAL CLUB. 421
no less good will and friendliness among them now, and desire
to help and welcome new-comers. He felt it had been a great
advantage to himself to belong to the Club.
The chairman then proposed a rhyming " toast," wishing
" Long life to the Club," and, at his request, the members rose in
a body and " made the welkin ring " in their concurrence with
the sentiment he had so deftly expressed.
To wind up a very pleasant evening, Dr. S pitta exhibited
upon the screen a series of lantern views of natural objects,
beautifully nature-coloured. Many of various flowers were
wonderful productions, with the colours unbelievably soft and
lifelike, and some of the insects were not less successful. The
meeting then broke up, many staying, however, to examine more
leisurely Mr. Watson Baker's unique specimens.
Unfortunately too late to be read at the meeting, a Marconi-
gram arrived from the late hon. secretary, Mr. W. B. Stokes, at
Montreal : " Congratulations five hundredth meeting." (Signed)
Stokes.
422
OBITUARY NOTICE.
MORDECAI CUBITT COOKE, M.A., LL.D., A.L.S.
(Born July 12th, 1825; died November 12th, 1914.)
It is with feelings of great regret we have to record the death, in
his ninetieth year, of Dr. M. C. Cooke, the " Father of the Club,"
which took place on November 12th at his residence in Southsea.
Dr. Cooke was born in 1825 at the village of Horning in
Norfolk, where his parents kept a general shop. From an early-
age he was dependent upon his own resources, und was in turn
employed as draper's assistant, teacher in a National school and
lawyer's clerk. As an assistant in the Indian Museum he at
last found congenial occupation, and when that institution was
abolished spent some time at the South Kensington Museum, in
the Mycological Department. He afterwards joined the Her-
barium at the Royal Botanic Gardens, Kew, and was for twelve
years (1880-92) in charge of the Cryptogamic Department ; in
the latter year he retired on a pension.
During this time he incorporated his own herbarium, con-
taining 46,000 specimens, with the existing collection at Kew,
as well as the collection of fungi presented to Kew by the
Rev. M. J. Berkeley. His figures of fungi, mostly coloured and
numbering 25,000 plates, are also at Kew.
His first important work was the Handbook of British Fungi,
in two volumes, published in 1871, followed by Mycogra'phia, or,
coloured figures of fungi from all parts of the world, 113 plates ;
Handbook of Australian Fungi ; and Illustrations of British
Fungi, 1,200 coloured plates. In addition to the above, over
300 articles on mycological subjects are credited to Dr. Cooke by
Lindau and Sydow ; for a period of fifteen years he also edited
Grevillea, a journal devoted to cryptogamic botany.
After his retirement in 1892 Dr. Cooke retained his interest in
fungi, and until 1904 attended the annual fungus foray of the
Essex Field Club. Recently his eyesight failed, though his mind
remained keen and active. He was honorary M.A. of Yale, and
OBITUARY NOTICE. 423
LL.D., and in 1903 he had the honour of being awarded the
gold medal of the Linnean Society.
In addition to his scientific publications, he was the author
and editor of a number of popular books in Natural History, and
was at the time associated with the publisher of Hardwicke's
Science Gossip, of which journal he was editor from its beginning
in 1865 until December 1871.
In the Journal of the Q.M.C. for November 1899 will be found
" Early Memories of the Q.M.C," a short paper contributed by
Dr. Cooke on the early history of the Club. Dr. Cooke was one
of the eleven members who attended the preliminary meeting
held on June 14th, 1865, and the meeting on July 7th, when
the Q.M.C. originated, and he was then elected one of its
first Vice-Presidents. He was President in 1882 and 1883,
and was elected an honorary member in 1893. He was always
a very active spirit at committees, meetings and excursions as
long as he attended ; his last recorded attendance was in May
1900.
Many of us will recall that our first excursions into the fairy-
land of science were made under the guiding hand of Dr. M. C.
Cooke.
424
Table for the Conversion of English and Metrical
Linear Measures; Yard and Metre at same Temperature.
1 -i-
2
mm.
1 +
A4
1 -r-
fl
1 +
A«
H
A*
12-70
27
940
53
479
79
321
125
203
*>
o
8-4 6
28
907
54
470
80
317
130
195
4
6-35
29
876
55
462
81
313
135
188
5
5-08
30
846
56
453
82
310
140
181
6
4-23
31
819
57
445
83
306
i 145
175
7
3-63
32
794
58
438
84
802
150
169
8
3-17
33
76!)
59
430
85
299
155
164
9
2-82
34
747
60
423
86
295
160
159
10
2-54
725
61
416
87
292
165
1 54
11
2-31
3(5
705
62
410
88
289
170
149
12
212
37
686
63
403
S!)
285
175
145
13
1-95
38
668
64
397
90
282'
180
141
14
1-81
31)
651
65
391
91
279
185
137
15
1-69
40
635
66
385
92
276
190
1 34
16
1-59
41
619
67
379
93
273
195
130
17
1-49
42
605
68
373
94
270
200
127
18
1-41
43
591
69
368
95
267
205
124
19
1-34
44
577
70
363
96
265
210
121
20
1-27
45
564
71
358
97
262
215
118
21
1-21
-if ;
552
72
353
98
259
220
115
22
115
47
540
73
348
99
256
225
113
23
1-10
48
529
74
343
100
254
230
110
24
1-06
49
518
75
339
105
242
; 235
108
25
1-02
50
508
76
334
110
231
i 240
106
A4
51
498
77
330
i 115
221
i 245
104
26
977
52
488
78
326
120
212
! 250
102
As the measurements of many microscopical objects are given in
fractions of an inch in English literature, and in metrical measure in
foreign works, the above table has been drawn up to facilitate com-
parison. Its use is obvious. Examples : l/7th inch = 3 63 mm., l/58th inch
= 438 ft, or -438 mm. For fractions smaller than 1 /250th inch that portion
of the table between the figures 26 and 99 may be used by cutting off
the last figure for hundredths, and the two last figures for thousandths.
Examples: 1 /270th inch = 94*0 p, or -0940 mm.; l/7900th inch = 321 p,
or "00321 mm. When that portion of the table between the figures 100
and 250 is used it is only necessary to cut off the last figure for thousandths
and the two last figures for ten thousandths. Examples : l/1350th inch
= 18-8 p, or -0188 mm., l/16500th inch = 1-54 p, or -00154 ram. The
conversion of millimetres into fractions of an inch is performed in the same
manner; thus, 529 p or -529 mm. = l/48th inch; 39-7 p or -0397 mm.
= l/640th inch ; 2-62 p or -00262 mm. = l/9700th inch ; 1-04 p or -00104
mm. = l/21500th inch; -977 p or -000977 mm. = l/26000th inch, and
so on. — E. M. N.
425
THE EARLY HISTORY OF THE QUEKETT MICRO-
SCOPICAL CLUB.
By R. T. Lewis, F.RM.S.
The Quekett Microscopical Club this year attains its Jubilee,
and, as no doubt many of its present members are unacquainted
with its early history, it has been thought that some account of
this would be of interest.
Hardwicke's Science Gossip was started in January 1865, and
in the May number of that periodical a letter appeared from
Mr. W. Gibson, suggesting that a Society for Amateur Micro-
scopists on similar lines to those of the Society of Amateur
Botanists (of which he was a member) would be desirable, as
being a means of bringing together those having similar tastes,
who could meet to discuss difficulties and assist one another in a
manner not provided for by the existing Society. Monthly meet-
ings and a small subscription were proposed, and persons interested
in the matter were invited to co-operate. The Editor of Science
Gossip gladly inserted this communication, and, being himself the
President of the Society of Amateur Botanists at the time,,
entered fully into the project, and together with Mr. W. M„
Bywater and Thomas Ketteringham met at the house of the
former in Hanover Square, and having discussed its feasibility,
decided that such a society should be established, and should be
named " The Quekett Club " after the name of the distinguished
Professor of Histology * who had died :a short time previously,
* John Thomas Quekett, b. 1815. In 1856 he succeeded Prof. Owen as
Conservator of the Hunterian Museum, and was appointed Professor of
Histology, which post he held until his death. He was elected F.R.S. in
1860, and died in 1861. He was Secretary of the Microscopical Society of
London for nineteen years. His Practical Treatise on the Use of the Micro-
scope is, or was, well known.
Journ. Q. M. C, Series II.— No 76. 30
426 R. T. LEWIS ON THE EARLY HISTORY OF THE
A meeting of twelve gentlemen known to be interested in the
microscope was therefore called, and took place on June 14th,
1865, at the offices of Mr. Robert Hardwicke in Piccadilly. This
meeting was attended by eleven out of the twelve summoned, the
chair was taken by Mr; M. C. Cooke, and on the motion of Mr.
W. Gibson it was unanimously resolved that such a Club should
be formed, and on the motion of Mr. E. Jaques it was also
unanimously decided that a provisional Committee of five gentle-
men, with Mr. Bywater as Secretary, should be appointed, and
charged with the duty of deciding as to the best means of carrying
out the object in view, and to report the result of their delibera-
tions to an adjourned meeting to be held on July 7th. This
meeting, which was held at St. Martin's National Schools, was
attended by about sixty gentlemen, when four suggestions made
by the Committee were discussed and severally put to the meeting,
it being eventually decided :
(1) That the new society should be called the Quekett
Microscopical Club.
(2) That the meetings be held on the fourth Friday of every
month.
(3) That the subscription be 10s. per annum, payable in
advance, and be considered due as from July 1st, 1865.
(4) That the business of the Club be conducted by a President,
two Vice-Presidents, twelve Members of Committee, a Secretary
and a Treasurer.
It was further decided that the provisional Committee should
be empowered to carry on the business of the Club and to receive
subscriptions until the appointment of regular officers had been
duly made ; the meeting was then adjourned until August 4th,
1865. At the adjourned meeting, which was also held at
St. Martin's Schools, a series of eleven By-laws were passed,
Dr. Edwin Lankester was elected the first President of the Club,
with Messrs. M. C. Cooke and P. le Neve Foster as Vice-Presi-
dents, Mr. Robert Hardwicke as Treasurer, Mr. W. M. Bywater
QUEKETT MICROSCOPICAL CLUB. 427
Secretary, and twelve members to serve on the Committee.
The first Ordinary Meeting was held on August 25th, 1865, in
the rooms at 32, Sackville Street, when the President took
the chair and gave an interesting inaugural address, and the
Quekett Microscopical Club was thus fairly started on what has
proved to be a successful career. The rapid increase in the
number of members soon made it apparent that the room in
Sackville Street was not large enough for the purpose, and the
Eighth Ordinary Meeting was held in the Library of University
College, kindly placed at the disposal of the Club by the Council
of the College, through whose courtesy the meetings continued to
be held there until 1889. Dr. Lankester was succeeded in the
Presidency by Mr. Ernest Hart, and it was in October 1866
that the suggestion was made that the proceedings of the
Club were now of sufficient importance to deserve some record,
and in the following month reports were taken by Mr. R. T.
Lewis, who has carried out this duty to the present time. The
earlier papers read at the meetings were in some instances
published in the Microscopical Journal or in Science Gossip, but
they were subsequently printed in the Journal of the Club,
which was commenced in 1868 under the editorship of Mr. W.
Hislop.
The first Soiree of the Club was held at University College
on January 4th, 1867, and notwithstanding a heavy fall of
snow and frost of exceptional severity, in consequence of
which vehicles were only to be obtained at a high premium,
it was attended by a large number of members and their
friends, and was deemed to have been a decided success.
Profiting, however, by the experience gained on this occasion,
future Soirees were held somewhat later in the year. The
number of members at the end of the second year of the
Club's existence was 273. Eleven Field Excursions took place,
the Cabinet contained 260 slides, and an "Exchange of Slides
Committee" was appointed.
428 R. T. LEWIS ON THE EARLY HISTORY OF THE
Mr. Arthur E. Durham was the third President, and held the
office for two years, during which period the Journal of the Club
made its first appearance, the extra meetings on the second
Friday in each month were commenced, and the first dinner took
place at Leatherhead, Mr. Suffolk's classes* were restarted, and
the number of members was reported as having reached 512. It
was towards the beginning of 1868 that a member of the Com-
mittee began to agitate for the admission of women as members,
a proposal strongly deprecated by his colleagues as being sub-
versive of the interests of the Club. This gave rise to considerable
opposition from the members generally, and much merriment
was created by the circulation of sketches by Mr. Suffolk and
Mr. Lewis, and by the issue of a skit purporting to be the
report of a meeting held two years ahead and embodying most
of the objections to the scheme. It was, however, formally-
proposed at the Ordinary Meeting in March 1868, Dr. Tilbury
Fox in the chair, but on the resolution being put it found only
two supporters, and was therefore negatived by an overwhelming
majority.
At the Annual Meeting in 1869 Mr. P. le Neve Foster suc-
ceeded Mr. Durham as President, but the latter took the chair
at the November meeting, when a handsome testimonial was
presented to Mr. Bywater on his retirement from the position
of Secretary, the duties of that office having been taken over
by Mr. T. C. White. In 1870 the members had increased so
much that it became necessary to reduce the number of invitation
tickets issued for the Annual Soiree, a charge being made for
* Mr. W. T. Suffolk conducted a class for beginners during the winter
of 1865-6 in a room at the Society of Arts, kindly placed at his disposal
for the purpose by Mr. P. le Neve Foster. At this he gave useful and
practical information on the management of the microscope, the mounting
of objects, etc. The class was suspended during the summer months, but
was resumed during the winter of 1866-7, and was fairly well attended
but as there is no later mention of it, I infer that it was not again started,,
but occasional demonstrations at the Gossip Meetings seem to have
taken its place.
QUEKETT MICROSCOPICAL CLUB. 429
those wanted in excess, the sale of which realised =£5 7s. Qd.,
a,nd this was given as a donation to University College Hospital.
The next four Presidents, Dr. Lionel S. Beale, Dr. Robert
Braithwaite, Dr. John Matthews and Mr. Henry Lee, each held
the office for two years. At the Annual Meeting in 1873
Mr. White retired and was succeeded by Mr. J. E. Ingpen, with
Mr. E. Marks as Assistant Secretary. Mr. Robert Hardwicke,
the first Treasurer of the Club, died in 1875, and was succeeded
in the office by Mr. F. W. Gay. In 1878 Prof. T. H. Huxley
was elected President, being followed by Dr. Spencer Cobbold in
1879, Mr. T. C. White in 1880 and 1881, Dr. M. C. Cooke in
1882 and 1883, Dr. W. B. Carpenter in 1884, Mr. A. D. Michael
in 1885, 1886 and 1887, and Mr. B. T. Lowne in 1888-9. The
<3ate of the Annual Meeting was altered to the last Friday in
February in 1888.
The last meeting in the Library of University College was
held on February 22nd, 1889, but the Council of the College
generously placed their Mathematical Theatre at the disposal
of the Club. This room, however, was found unsuited to their
purpose, and arrangements were made for removal to 20, Hanover
Square. This necessitated a change of the meeting nights to
first and third Fridays, and no Ordinary Meetings were after-
wards held in July and August. The history of the Club during
the last twenty-four years need not be recorded here, as all
particulars are to be found in the reports, and are doubtless
well known to the majority of the members. Briefly, however,
since its commencement in 1855, it has had twenty-three Presi-
dents, seven Secretaries, and has published sixteen volumes of its
Journal.
Of the original members but few are now left, and of those
who joined in the first year only two now are seen at the
meetings. Mr. W. Gibson, whose suggestion led to the Club's
formation, does not appear to have contributed to the pro-
ceedings, though he continued to be a member for eighteen
430 R. T. LEWIS, EARLY HISTORY OF QUEKETT MICROSCOPICAL CLUB,
years. Mr. M. C. Cooke, who took the chair at the preliminary
meetings, was elected an honorary member in 1893, and con-
tinued to take a lively interest in the well-being of the Club up
to the time of his death, which occurred in his ninetieth year,
only a few months ago.
Journ. Qutkett Microscopical Club, Str. 2, Vol. XJL, No. 7(5, April 1915.
431
A NEW COPEPOD FOUND IN WATER FROM HOLLOWS
ON TREE TRUNKS.
By D. J. Scourfield, F.Z.S., F.R.M.S.
{Read November 24th, 1914.)
Plates 24 and 25.
The search for plants and animals in unusual and unlikely
places is always interesting, and may be sometimes richly re-
warded. As a case in point, and the one which led directly to the
discovery of the new species of Copepod that I wish to describe
in this paper, we may consider what has been done in the
elucidation of the fauna living in the little natural cups formed
by the bases of the leaves of plants belonging to the Order
Bromeliaceae, i.e. the order to which the pine-apple belongs.
It was in 1879 that the celebrated naturalist Fritz Miiller,
who was at that time associated with the National Museum in
Rio de Janeiro, called attention to the fact that the water con-
tained in the little cups just referred to was tenanted by various
forms of animal life. In particular he described a new Ostracod,
representing a new genus, Elpidium bromeliarum, which occurred
almost constantly in association with the Bromeliaceous plants
in the forests of Brazil, and strangely enough was to be found
in no other situation (5, 6, and 7).
Since that date a number of other investigators have from
time to time examined these little collections of water retained
by the leaves of Bromeliaceous plants, and I may here mention
that soon after I became acquainted with the work of Fritz
Miiller I commenced to look for Entomostraca in these situa-
tions at the Royal Botanic Gardens, Regent's Park, and at Kew.
My curiosity was gratified by finding the remarkable blind
Copepod, Belisarius viguieri, which had not previously been
found in this country.* In recent years still more attention
* Kecorded and figured in Joum. Q. M. C, vol. viii., November 1903,
p. 539, and vol. ix., April 1904, PI. 2 (15). For further notes on this species
see also The Wild Fauna and Flora of the Royal Botanic Gardens, Kew,
p. 20 (16).
432 D. J. SCOURFIELD OX A NEW COPEPOD FOUND IN
has been given to the subject owing to the endeavour to discover
the life-histories of mosquitoes and other insects supposed to be
connected with the dissemination of tropical diseases. Last year
a very elaborate paper was published by Picado (8), in which
he gives details of the facts previously elucidated, and of his
own work on this subject in Costa Rica. It appears that no
less than about 250 species of animals have been found living
in this peculiar environment, 49 being new to science. They
belong to almost all groups of Invertebrates, but naturally
insects and their larvae predominate. The Amphibia are also
represented. A very full account of this paper has been recently
published by H. Scott in the Zoologist (12).
When once this peculiar habitat had been pointed out, it was
natural that somewhat similar situations should be searched, and
records have indeed been made of animals found living in the
pitchers of Pitcher-plants and Sarracenias, the holes occurring
occasionally in bamboos, the tops of palm trees, and in various
other places.
It occurred to me that perhaps the little collections of water
which are sometimes to be found in the hollows and crevices
on the trunks and exposed roots of trees might possibly be
inhabited by some member or members of the Entomostraca,
the group in which I am more particularly interested. This
proved to be the case ; at least I am now able to report that
on several occasions I have found the minute Copepod about
to be described in such little reservoirs of water on trees in
Epping Forest. Up to the present it has been found nowhere
else, and, on the other hand, I have never found any other
species of Entomostraca in the same places.
The new species evidently belongs to the Harpacticid genus
Moravia T. and A. Scott, and I propose to call it M. arboricola
on account of its tree-dwelling habit.
The genus Moravia is very closely allied to the well-known
genus Canthocamptus, and is, in fact, even now included in the
latter by some authors. It was instituted by T. and A. Scott in
1893 (14) for a species found in Loch Morar, in Scotland, which
they named M. andevson-smithi, believing it to be new, but
which subsequently proved to be identical with C anthocamptus
brevipes Sars, described thirty years previously (11). A month
or two later in the same year, 1893, Mrazek described as new
WATER FROM HOLLOWS ON TREE TRUNKS. 433
the same species, placing it with two others which were really
new to science, in a new genus, Ophiocamptus, thus showing that
he also recognised the necessity of separating Sars's C. brevipes
-and closely allied forms from the old genus C anthocamptus (4).
The characteristics of the genus Moraria are chiefly as
follows : Body very elongated, almost vermiform. Rostrum
broad. First antennae seven-jointed. First four pairs of feet
with three-jointed outer and two-jointed inner branches. Inner
branches of first pair of feet only a little shorter than the outer
branches, with the basal rather longer than the terminal joint.
Inner branches of the second, third, and fourth pairs of feet
only a little longer than the first joint, or at most only as long
as the first two joints of the outer branches. Furca well de-
veloped, each branch tapering considerably from base to tip, and
usually (? always) furnished with a strong longitudinal chitinous
ridge on the dorsal surface.
So far as I can ascertain, eight species of Moraria have hitherto
been described and two others referred to, but not described.
They are as follows :
M. brevipes (G. 0. Sars), 1863 = C anthocamptus brevipes G. 0.
Sars, 1863 (11); M. anderson-smithi T. and A. Scott,
1893 (14) ; Ophiocamptus sarsi Mrazek, 1893 (4).
M. mrdzeki T. Scott, 1903 (13), new name only = Ophio-
camptus brevipes Mrazek, 1893 (4).
M. poppei (Mrazek), 1893 (4) = 0. poppei Mrazek, 1893 (4).
M. muscicola (Richters), 1900 (9) = 0. muscicola Richters,
1900 (9).
M. schmeili van Douwe, 1903 (3).
M. mongolica (Daday), 1906 (1 and 2) = 0. mongolicus Daday,
1906 (1 and 2).
M. wolfi Richters, 1907 (10).
M. quadrispinosa Richters, 1907 (10).
M. sp. 1 Richters, 1907 (10).
M. sp. 2 Richters, 1907 (10).
Most, if not all, of the above have been found living in wet
-or damp mosses ; some, in fact, have hitherto been found in no
other situations. Only the first three have been found in the
British Isles.
434 D. J. SCOURFIELD ON A NEW COPEPOD FOUND IN
Moraria arboricola sp. nov.
Female. — Body (fig. 1) long and vermiform, divided into nine
free segments, the first being the longest and the sixth (first-
abdominal) the second in length. Rostrum broad. Eye red or
brownish red, moderately large as a rule, but rather variable in
size and in outline. Dorsal plate on carapace rather variable
in shape, usually more or less rectangular with rounded anglesr
slightly broader in front than behind. Posterior margins of all-
segments smooth on dorsal surface. On ventral surface abdominal
segments (fig. 16) armed as follows: 1st, with two widely
separated groups of about five teeth ; 2nd, with a row of teeth
from one-third to half width of segment, sometimes with central
teeth missing, thus leaving two isolated groups; 3rd, with a row
extending almost across segment ; 4th (last), with a row com-
pletely across segment and a little way round sides, except for
the slight interruption caused by the posterior median notch.
Anal plate or operculum (see fig. 15) more or less semicircular^,
with smooth but slightly wavy edge, and with faint dark and
light bands radiating towards the edge, showing probably that
the plate is very slightly corrugated.
In the stage before the adult the edge of the anal plate is not
smooth, but furnished with a few very minute teeth, widely but
somewhat irregularly spaced (fig. 13). In the still earlier stages
the teeth are rather larger (fig. 12). The presence of teeth on
the anal plate in the young stages of M. brevipes, which also
has smooth edges in the adult, has been noted by Mrazek (4).
Branches of furca (figs. 14 and 15) moderately long and taper-
ing considerably, with a prominent chitinous ridge on the dorsal
surface, ending posteriorly in a blunt tooth from the base of
which springs a spine directed upwards. Outer edges armed
with two strong spines, the proximal with a minute accessory
spine at its base. Inner edges with two curved rows of minute
teeth, terminating dorsally in little teeth on the chitinous plate.
Posterior edges with a row of teeth on the ventral surface,
covering bases of terminal setae. Terminal setae usually quite
smooth, three on each furcal lobe, inner very small, outer not
quite half the length of the median, which again is about half
the body length. The outer and median setae, especially the
latter, somewhat bulbous at the base.
WATER FROM HOLLOWS ON TREE TRUNKS. 435
First antennae (fig. 2) rather short and seven-jointed, with the
olfactory seta, on the fourth joint reaching only to about the
middle of the last joint. Second antennae of the usual type
with the accessory branch (fig. 3) very small, one-jointed, bearing
three setae at the tip. First pair of feet (fig. 4) small, with
three-jointed outer and two-jointed inner branches. Inner
branch not quite so long as outer, with one of the two terminal
setae extremely long and curved at the tip. Second, third, and
fourth pairs of feet (fig. 6) very similar to one another with the
three-jointed outer branches larger than in the feet of the first
pair, but with the two-jointed inner branches smaller, being only
a little longer than the basal joints of the outer branches. The
second joints of the inner branches of the second and third pairs
of feet carry three terminal spines, the corresponding joint of the
fourth pair only two. Fifth feet (fig. 8) consisting of two joints,
the basal being extended on the inner side considerably beyond
the broadly ovate second joint. Inner part of basal joint armed
with six spines somewhat flattened, with rounded tips of the
type found in M. brevipes Sars, but not quite so broad or blunt.
The fourth and fifth spines from the inner edge arise from a
little sub-rectangular projection which has the appearance of a
pseudo-joint. A finely pointed spine projecting outwards arises
as usual from the lower corner of the outer edge of the joint.
The second joint armed with four spines, the innermost being
of the same type as those on the basal joint, and the other
three being finely pointed and not flattened. The median of
these three turns outwards across the outer spine. There is a
little thorn on the inner edge of this joint just above the inner-
most spine. None of the spines on the fifth feet are plumose,
but a single barb usually occurs on the fifth and sixth from
the inner edge, as indicated in fig. 8. Earlier stages of the fifth
feet are shown in figs. 10 and 11.
Eeceptaculum seminis (fig. 18), lying immediately behind and
usually covered by the fifth feet, somewhat complicated in
structure, consisting apparently of two lateral highly chitinised
convoluted chambers or tubes and a median membranous or
muscular cavity, the latter sometimes rhythmically contracted
and expanded by two lateral muscles, thus forming for a time
a kind of pulsating organ.
Chitinous integument of body and furca almost everywhere
436 D. J. SCOURFIELD ON A NEW C0PEP0D FOUND IN
covered with minute pits only readily noticeable under a 1/1 2th in.
objective (see figs. 14, 15, 16 and 17). Dorsal surface of most
of the thoracic and abdominal segments with lines of excessively
minute teeth arranged in various ways characteristic of the
different segments, often giving the impression of a series of
scales (fig. 17).
Eggs much elongated while in the body, only one or two on
either side, forming two lateral lines extending sometimes from
the second free thoracic to the last abdominal segment. As no
ovisac has yet been observed, it may be that the eggs are
deposited upon extrusion and not carried about.*
Length without terminal setae, l/50th in. to l/40th in.
Male. — Very similar to female in general appearance, but body
divided into ten free segments, the first longest and the seventh
to tenth next in length and sub-equal. Posterior margins of
abdominal segments armed on ventral surface as follows : 1st,
with two widely separated groups of two spines each situated
on a slight prominence forming rudimentary sixth feet ; 2nd and
3rd, with a row of teeth about half the width of the segment ;
4th and 5th, with a row across whole width of segment. Anal
plate as in female, also furcal lobes and terminal setae, except
that the two little curved rows of teeth on the inner sides of
the furca are not so well developed. The edge of the anal plate
is toothed in the young stages as in the female.
First antennae modified in the usual way with no very
characteristic features. First four pairs of feet almost exactly
as in female except that the inner branches of the second, third
and fourth pairs are larger and specially modified as follows :
2nd (fig. 20), with a thick slightly curved process (? enlarged
spine) projecting downwards from the anterior face of the basal
joint and probably forming with the second joint a pincer like
apparatus; 3rd (fig. 21), with second joint carrying two strong
terminal setae, one of which is about a third the length of the
other and shaped like the blade of a knife, and the first joint
bearing a very large trailing spine curved towards the base ;
4th (fig. 7), with both joints leaf-like, the second having a
curiously twisted little spine on the lower outer margin. Fifth
feet (fig. 9) simpler than in female, the slightly extended part
of the basal joint with only two short spines, the second joint
* See note on p. 440.
WATER FROM HOLLOWS ON TREE TRUNKS. 437
of a more elongated and rectangular shape with a spine arising
from near the base on the inner edge, and four spines from the
distal edge, the third of which from the inner side turns outwards
across the outer spine. None of the spines are of the flattened
blunt type present on the fifth foot of the female.
The spermatophore (fig. 19) is flask or retort-shaped with very
thick walls, the outlet tube being embedded for a part of its
length in a mass of cementing material.*
Length without terminal setae, about l/50th in.
As regards the habits of M. arboricola not very much can be
said. They are not very good swimmers, their movements in the
open water being best described, perhaps, as an active wriggling
assisted by the beating of the feet rather than as true swimming
produced chiefly by the action of the feet. On the whole they
seem to prefer moving downwards more than upwards when free
from support. They can, however, cling very strongly even to
glass, and often in this way travel about the sides of the vessel in
which they are kept. Very often I have found that they have
clung to the inside of the pipette whilst being transferred from a
bottle to the live-box. When placed in a watch-glass I have noticed
on several occasions that a tap on the glass had the effect of suddenly
stopping their movements just as if they were feigning death.
As already mentioned, M. arboricola has only been found in
little hollows on tree trunks in Epping Forest, and so far only
in the Theydon Bois and High Beech districts, f The first
specimens were found in 1904 near Theydon Bois, and since that
date the species has been obtained many times either actually
living in the water and sediment or developing out of the black
earthy deposit taken from dry hollows and placed in water. It
has happened on several occasions that no trace of the animals
could be found in the first instance, but that after several weeks,.
* This peculiar mass can be seen in the same relative position while the
spermatophore is still within the body of the male. It seems therefore to
be a constant character and not merely a temporary feature produced at
the time of attachment to the female.
t The fact that so many of the Epping Forest trees have been pollarded
in bygone times has had the effect of largely increasing the number of
cavities and hollows on their heads and trunks in which water can
accumulate in wet weather, thus rendering the district a particularly
favourable one for the study of the fauna and flora of such a peculiar
environment. The systematic investigation of this fauna and flora is much
to be desired, and could scarcely fail to vield valuable results.
438 D. J. SCOURFIELD ON A NEW COPEPOD FOUND IN
or even a month or two, specimens have begun to appear. From
the fact that the females have not been observed carrying ovisacs *
it seems possible that the eggs are dropped into the sediment to
lie dormant for a time, or even to be dried up and so perhaps
blown about by the wind. This might account for their distribu-
tion from one tree to another, although it is very probable that
insects, of which a number of forms occur in the same situations,
may also be a means of dispersal. In this connection and also in
relation to their peculiar habitat the wonderful vitality of the
animals may play an important role. They seem capable of
living for a very long time in quite small quantities of water
and with scarcely any food. On one occasion specimens continued
in evidence for four and a half years in a 3-in. x 1-in. glass tube
in which the collection had been brought home. The tube con-
tained nothing in the way of food, except the very innutritious-
looking original sediment, and nothing was added during the
whole time but a little clean water. Individual specimens, too,
have been kept for months in very small tubes with only the
merest trace of sediment and have remained perfectly active.
Such powers of endurance must evidently be of the greatest
value to them in their natural surroundings.
Literature Referred to.
1. Daday, E. von. Edesvizi mikroskopi allatok mongoliabol.
Math. Termt. Ert., Vol. 24, 1906, pp. 34-77.
2. Daday, E. von. Beitrage zur Kenntnis der Mikrofauna des
Kossogol-Beckens in der Nordwestlichen Mongolei. Math.
Nat. Berichte aus Ungarn, Vol. 26, 1913, pp. 274-360.
3. Douwe, C. van. Zur Kenntniss der Sussuasser-Harpacticiden
Deutschlands. Zool. Jahrbucher. A bt. fiir Systematize, etc.,
Vol. 18, 1903, pp. 383-400.
4. Mrazek, A. Beitrag zur Kenntniss der Harpacticiden fauna
des Siisswassers. Zool. Jahrbucher. Abt. f. Systematic,
etc., Vol. 7, 1893.
5. Muller, F. Descripgao do Elpidium bromeliarum crustaceo
da familia dos Cythei icleos. Arch. Museu National do
Rio de Janeiro, Vol. 4, 1879, pp. 27-34.
6. Muller, F. Phryganiden-Studien. 3. Wasscrthiere in den
Wipfeln des Waldes. Kosmos, Vol. 4, 1879, pp. 390 392.
* See note on p. 440.
WATER FROM HOLLOWS ON TREE TRUNKS. 439
7. Muller, F. Wasserthiere in Baumwipfeln. Elpidium
bromeliarum. Kosmos, Vol. 6, 1880, pp. 386-388.
8. Picado, C. Les Bromeliacees epiphytes, considerees comme
milieu biologique. Bull. Scientifique de la France et de
la Belgique, Vol. 47, 1913, pp. 215-360.
9. Richters, F. Bfitrage zur Kenntnis der Fauna der
Umgegend von Frankfurt a. M., III. Ophiocamptus
muscicola n. sp., ein moosbewohnender Copepode. Bericht
der Senckenbergischen N aturforschenden Gesellschaft, 1900,
pp. 36-39 (also further notes in the same publication,
1902, pp. 6-7).
10. Richters, F. Die Fauna der Moosrasen des Gaussbergs und
einiger siidlicher Inseln. Deutsche Slid-polar Expedition,
1901-1903, Vol. 9, 1907.
11. Sars, G. O. Oversigt af de indenlandske Ferskvands Cope-
poder. Vidensk.-Selsk. i Christiania Forhandl. for 1862
(Aftr.), 1863, p. 24.
12. Scott, H. The Fauna of "Reservoir-plants." Zoologist,
Vol. 18, 1914, pp. 183-195.
13. Scott, T. Some Observations on British Freshwater Har-
pacticids. Annals and Magazine Nat. Hist., Series 7,
Vol. 11, 1903, pp. 185-196/
14. Scott, T. and A. On some new or rare Scottish Entomo-
straca. Annals and Magazine Nat. Hist., Series 6,
Vol. 11, 1893, pp. 210-215.
15. Scourfield, D. J. Synopsis of the known species of British
Freshwater Entomostraca, Part II. and Part III. (Plate).
Journal Quekett Micro. Club, Series 2, Vol. 8, 1903,
p. 539, and Vol. 9, 1904, p. 44.
16. Scourfield, D. J. The Wild Fauna and Flora of the Royal
Botanic Gardens, Kew. Crustacea, Entomostraca.
Bulletin of Miscellaneous Information, Additional Series V.
(Royal Botanic Gardens, Kew), 1906, pp. 14-20.
Explanation of Plates 24 and 25.
Moraria arboricola sp. nov.
Fig. 1. Dorsal view °, x 200.
,, 2. First antenna ? , x 700.
,, 3. Accessory branch of second antenna
55
55
»
440 D. J. SCOURFIELD ON A NEW COPEPOD.
Fig. 4. First foot ? , x 6C0.
5. Seta on inner angle of basal joint of first foot <$ .
6. Fourth foot ?, x 600.
7. Inner branch of fourth foot J1, x 1000.
„ 8. Fifth foot ?, x 1000.
„ 9. ,, „ S, x 700.
10. „ „ young ? (antepenultimate stage).
11. „ „ „ $ (penultimate stage).
12. Anal plate, young (three stages before adult).
13. „ „ „ (penultimate stage).
14. Last abdominal segment and furca from side ?/x 700,
15. „ „ ,, ,, „ dorsal view ? , x 700,
16. „ 3 ,, segments ,, „ ventral view ¥ (some-
what flattened and contracted), x 350.
17. First and second abdominal segments, dorsal view ?y
X 350.
18. Receptaculum seminis $, x 900.
19. Spermatophore, x 400.
20. Inner branch of second foot $ (from left side), x 500.
21. „ „ „ third „ <?, x 500.
5>
J)
))
>>
55
55
Note added April 1915.
A single individual of M. arboricola has now been seen carrying
an ovisac containing four eggs, the latter being almost perfect
spheres l/500th inch in diameter. The ovisac itself was very
delicate and soon became detached, and also separated into two
parts, each containing two eggs, by the movements of the animal
when lightly held in the live-box.
Nauplii in various stages have also been seen. The earlier
forms exhibit a somewhat elaborate structure on the back, con-
sisting of three pairs of papillae with pointed tips lying between
two strong lateral thorns. Whether this is characteristic of the
species or not is unknown.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., N: 76, Ap 1915.
Journ.Q.M
Sep. 2 ai,P1.24.
Scourfield del. ad
■-Newman lith.
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Jour-
Ser.2 25.
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.
j'/fVl/Vi'Wi -YJCWW
ScourfielddeLadnat. West,Newn u
kria arborieola sp.nc
441
SOME DETAILS IN THE ANATOMY OF THE RAT-FLEA,
CERATOPHYLLUS FASCIATUS BOSC.
By Prof. E. A. Minchin, M.A., Hon. Ph.D., F.R.S.
{Bead January 2Qth, 1915.)
Plates 26-32.
During the past five years I have been engaged, in collaboration
with a friend, upon investigations, recently published,* into the
development of the rat-trypanosome in its invertebrate host the
rat-flea (Ceratophyllus fasciatus). In the course of this investi-
gation we have dissected and examined some 1,700 fleas ; and
although these dissections were not undertaken with the
primary object of studying the anatomy of the flea, but only
with the intention of extracting and examining those organs of
the flea likely to contain stages of the trypanosome, it goes
without saying that we have not pulled so many fleas to pieces
without gaining some insight into the structure of the insect,
and it seemed to me worth while to study some anatomical points
of structure in more detail and in special preparations. Some
parts of the flea are very interesting as regards their structural
relations and make very beautiful microscopic preparations which
can be mounted with very little trouble. I thought it might
interest the members of the Club if I laid before them a brief
account of some points of flea-anatomy seen by the way — obiter
visa, if I may use the expression,
Before describing these observations, I wish it to be clearly
understood that this paper does not pretend to give a complete
anatomical description either of the flea as a whole or even of
the systems of organs that are dealt with. There are many
structural details which could only be made out by sections, and
I have had no leisure for the task of section-cutting, always a
difficult and laborious undertaking in the case of insects, on
account of the toughness of the chitinous cuticle, which cannot
* Minchin and Thomson, " The Rat-trypanosome, Trypanosoma lewisi,
in its Relation to the Rat-flea, Ceratophyllus fasciatus" Quarterly
Journal of Microscopical Science, Vol. LX., Part 4, 1915.
Journ. Q. M. C, Series II. — No. 76. 31
442 E. A. MINCHIN ON SOME DETAILS IN THE ANATOMY OF
be dissolved out. I do not propose to describe any details here
which cannot be verified by an observer possessing a dissecting
microscope * and a pair of mounted dissecting needles — and a
flea ! In fact the results obtained by me and set forth here are
based entirely on what may be termed " needlework."
Before proceeding to anatomical descriptions, I may give a
brief account of the technique I have employed. The flea at
liberty is, I need not say, an active and elusive insect. But
when placed on the surface of water, he is perfectly helpless, and
floats there without being able to escape and without drowning
for at least twenty-four hours, provided there is no soap in the
water ; if there is a trace of soap the cuticle of the flea is wetted
and the insect sinks and is soon drowned. (This hint may be
borne in mind as being often useful in the home.)
Having therefore caught your flea, put it on the surface of
some water and keep it until you can proceed further with your
operations. An expeditious way of catching the flea is to get
it to hop straight on to the surface of water. In doing this
remember that a flea always hops by preference away from the
source of light, never towards it.
When it is desired to dissect the flea it should be gathered off
the surface of the water with a fine forceps and placed in a drop
of physiological salt-solution (0*75 gramme sodium chloride in 100
cubic centimeters of distilled water) on an ordinary microscopical
slide, which is then placed on the stage of the dissecting
microscope.
For the dissection I use two fine needles mounted in wooden
handles. Each needle after fixing in the handle is ground down
further on an ordinary hone. One of them is ground to a fine
sharp point, the other to a flat cutting edge. For preparing the
flat-edged needle, I first take a penknife and pare the extremity
of the wooden handle on both sides so that it is shaped like an
ordinary brad-awl. I then rub the needle down on the hone in two
planes parallel to the two cuts made in the handle, checking the
process under the dissecting microscope and trying to get a
rounded cutting edge, not an edge which terminates in a straight
line like an ordinary chisel. The object of paring the wooden
handle is both to guide the hand when rubbing down the needle
* I have used in all my work a Greenough binocular dissecting
m'croscope made by Zeiss.
THE RAT-FLEA, CERATOPHYLLUS FASCIATUS BOSC. 443
on the hone, and also to distinguish the flat-edged needle from
the pointed one. When dissecting I use the pointed needle in
my left hand for holding the object, and the flat-edged needle in
my right hand for cutting. The needles should be pushed far
into the wooden handle, so that only a short length is free, other-
wise the needle is too springy and is liable to snap under
pressure.
The flea was left in the drop of salt-solution, where it is kicking
about violently and may succeed, if not watched, in getting out
on to the slide and hopping off*. It is therefore best to begin by
decapitating the flea. This can be done by holding it still with
the pointed needle and snipping off the head with the flat-edged
needle. The dissection can then be proceeded with in a manner
free from haste or anxiety.
I will describe now a method of making permanent preparations
of the organs of the flea which I have found very useful. There
is not a single detail of anatomy described in this paper which I
could not demonstrate to a sceptic in my permanent preparations *
at a moment's notice. Let us take the abdominal nervous system,
for example. The complete nervous system of the flea consists,
as in other insects, of the three sets of nerve-ganglia: (1) the
cephalic ganglion -complex, or brain, situated in the head dorsal
to the digestive tract (supra-oesophageal) ; (2) three pairs of
thoracic ganglia, corresponding to the three thoracic segments :
(3) a chain of abdominal ganglia extending into the abdomen.
Parts (2) and (3) are ventral to the digestive tract and constitute
a continuous chain of pairs of ganglia, but the two ganglia of any
given pair are fused together so as to appear like a single ganglion-
mass. Each pair of ganglia is connected with the pair next
behind or in front by a pair of stout nerves, known as " connec-
tives," and it can be plainly seen that these connectives remain
distinct in each pair, and are not fused together like the ganglion-
pairs (PI. 26). The first pair of thoracic ganglia is connected
with the brain by a pair of peri-oesophageal connectives. From
the ganglia are given off* nerves to the various organs of the body.
It is almost impossible to dissect out the brain, and to study its
structure and relations sections would be necessary. It is difficult,
but by no means impossible, to dissect out the thoracic ganglia.
Major Christophers, I. M.S., who worked for a time in my
* These preparations are now the property of the Club.
444 E. A. MINCHIN ON SOME DETAILS IN THE ANATOMY OF
laboratory at the Lister Institute, made some beautiful dissections
of the ventral nervous system of the flea, showing both thoracic
and abdominal ganglia in continuity. On the other hand, it is by
no means difficult to dissect out the abdominal chain in its whole
length, up to and including the large metathoracic ganglia, the
ganglia of the jumping legs. To do this the flea should be held by
the thorax with the pointed needle, while with the flat -edged needle
the abdominal segments are carefully detached and pulled off
from behind forwards successively, until only the thoracic segments
are left. If the operation has been successfully performed, and
the abdominal segments together with the contained digestive
and reproductive organs removed, the abdominal chain of ganglia
will be seen proceeding from, and adhering to, the hindmost
thoracic segment. With practice the complete severance of the
abdomen and its organs from the thorax can be effected with one
pull.
Now take another slide and place on it a cover-slip (| inch
square). Place the slide and cover-slip on the stage of the dis-
secting microscope, put a quite small drop of salt-solution on the
cover-slip, and transfer the thorax of the flea from the slide on
which it was dissected to the small drop of fluid on the cover-slip,
and there proceed with the dissection. The big metathoracic
ganglion-mass can be seen quite plainly in the hindermost part
of the thorax, with the abdominal chain of ganglia proceeding
from it. With the needles the metathoracic ganglion must be
carefully dissected out and set free from the thorax ; this operation
is not at all difficult, though it requires both skill and practice to
dissect out the first two thoracic ganglia as well, in unbroken
continuity with the rest of the ganglionic chain. If during the
dissection the cover-glass slips about on the slide, it can be fixed
quite firmly by letting a tiny drop of distilled water run in between
cover-glass and slide, but I avoid this as a rule, because it makes
it difficult to get the cover-slip off later on.
When the dissection has been completed, the fragments and
debris of the thorax should be removed and cleaned up as much
as possible, leaving the nervous system in the small drop of fluid
on the cover -slip. Now the cover-slip must be lifted carefully off
the slide and all superfluous moisture drained off it, so as to leave
the nervous system stranded on the cover-slip, as near the centre
as possible. The fluid can be drained off either by tilting the
THE RAT- FLEA, CERATOPHYLLUS FASCIATUS BOSC. 445
cover-glass and letting the salt-solution run off, or, if the nervous
system shows a tendency to run off with the fluid, by holding the
cover-glass flat and carefully mopping up all superfluity of fluid
with a small piece of filter-paper. The object to be attained is to
leave the specimen stranded on the cover-glass and to drain off as
much of the salt-solution as possible, in order that by capillary
attraction the object may be pressed against the cover-slip ; but
on no account must the fluid be allowed to dry completely. When
this has been done the cover-slip is inverted, so that the object is
on its lower side ; and then it is dropped face downwards quite
flat on to the surface of some fixative fluid.
Various fixatives can be used, but I have nearly always made
use of 5 per cent, sublimate-acetic — that is to say, saturated
solution of corrosive sublimate in distilled water, 95 volumes,
mixed with glacial acetic acid, 5 volumes. When fixing the
preparation some of the fixative is put into a large watch-glass
or clock-glass and the cover-glass with the adherent object is
dropped on to it and remains floating on the surface of the
solution. In nine cases out of ten the object remains firmly
adherent to the under side of the cover-glass, if one has hit the
happy medium in draining off the fluid in which it was dissected
out. If superfluity of the salt-solution remains, the object will
come off; if it has been allowed to dry up altogether, the
preparation is ruined.
The cover-glass with the adherent organs can now be mani-
pulated just as if it was a smear, lifting the cover-slip with an
ordinary forceps and transferring it from one liquid to another.
After the preparation has been fixed in the sublimate-acetic for
some time, say from 10 minutes to an hour, it can be brought
up through successive strengths of alcohol in watch-glasses
(10 per cent., 30 per cent., 50 per cent, and 70 per cent.) to
90 per cent, alcohol, in which it should be left for a longer time
(preferably over night, or as long as is convenient) in order that
the preparation may be well hardened and the corrosive sublimate
thoroughly dissolved out. In the stronger alcohols the cover-slip
will sink, but it rests on its corners on the rounded bottom of
the watch-glass and there is no contact or pressure on the object,
which of course is on the under side of the cover-slip. It is now
apparent why square cover-slips must be used, since they rest on
their corners and can be easily picked up with the forceps :
446 E. A. MINCHIN ON SOME DETAILS IN THE ANATOMY OF
round cover-slips would be in contact with tbe watch-glass round
their whole edge, and be very troublesome to lift up with the
forceps or in any other way.
Sometimes the object comes away loose from the cover-slip in
the sublimate-acetic. When this annoying event takes place,,
put the cover-slip into a watch-glass and cover it with 30 per cent,
alcohol; then draw up the object from the sublimate-acetic
mixture with a glass pipette of sufficiently wide calibre and place
it on the upper surface of the cover-slip in the alcohol. Then lift
up the cover-slip carefully with a forceps, taking care the object
does not float off the cover-slip to one side or the other, but
remains stranded on the cover-slip again. Then drain off the
alcohol, invert the cover-slip, and drop it face downwards into
50 per cent, alcohol in another watch-glass. This time the
rebellious object always sticks to the cover-slip. In all cases the
cover-slips should be handled delicately while in the sublimate-
acetic or in the weak alcohols, since a too violent jerk may
dislodge them ; but I have never known an object to come loose
after it has got so far as the 70 per cent, alcohol.
I have described this method in full detail because I have
found it extremely useful for making permanent preparations
of dissections. In the flea, for example, it is very easy to dissect
out and mount in this way the entire male reproductive system,
from testes to penis, and so display every detail of it ; and since
the preparation is adherent to the cover-slip, any powers of the
microscope, even immersion lenses, can be focused on to it for
study of minute details. The principle of the method is that
cellular tissues, having been pressed firmly but gently against
the glass by capillary attraction, adhere to the glass by their
own stickiness ; and when the preparation has been well fixed
and hardened, the coagulation of the albumins glues the organs
so firmly that they cannot be detached without breaking
them. Naturally this does not apply to chitinous organs,
which are not wetted by water, and can never be made to stick
in this way.
The preparations, after having been fixed and hardened, can
be mounted unstained, or can be stained first in any way desired..
Unstained preparations are best for showing internal details of
the chitinous cuticle or skeleton ; stained preparations for
showing the cellular structure of the tissues and soft parts ; the
THE RAT-FLEA, CERATOPHYLLUS FASCIATUS BOSC. 447
one method of preparation supplements the other. For staining
an alcoholic stain is preferable, since prolonged soaking in watery
stains might produce maceration and cause the object to become
detached again from the cover-slip. I have always used Gren-
adier's alcoholic borax-carmine, in which the objects are stained
for about five minutes, and then transferred to acidulated alcohol
(0*1 per cent, hydrochloric acid in 70 per cent, alcohol), in order
to extract all the carmine stain from the cytoplasm of the cells
and leave it only in the nuclei. If the stain be not thoroughly
extracted in this way the preparation will be very opaque, and
I find it best to leave the objects in the acidulated alcohol for about
forty-eight hours, changing the fluid occasionally. I believe this
method could be improved upon, and that Mayer's alcoholic
paracarmine * would give a more transparent stain, and one
more easily extracted. Some of the well-known haematoxylin
mixtures would probably also give good results.
The stained or unstained preparations are then finished off by
passing them into absolute alcohol, then into oil of cloves or any
other of the ordinary clearing reagents, and finally into Canada
balsam. The cover- slips can be mounted over well-slides or —
preferably, in my opinion — on ordinary slides, with the precau-
tion of supporting the corners of the cover-slip on wax feet or in
some other way, in order that the objects may run no risk of
being crushed between slide and cover-slip.
I will now proceed to set forth some of my observations on the
anatomy of the flea, noting, as a preliminary, that all my state-
ments apply to the common rat-flea, Ceratophyllus fasciatusy
the only species I have dissected. Other species of flea may
perhaps show slight differences in some points.
It is also my pleasant duty, at this point, to express my warm
thanks to Miss Mabel Rhodes, artist at the Lister Institute, for
kindly executing the drawings of my dissections which accompany
this paper. They were all drawn with the camera lucida from
the actual preparations.
I. The Abdominal Nervous System.
The method of dissecting out the abdominal chain of nerve-
ganglia has been described above. It is one of the easiest
* For an account of these stains and how to prepare them see Bolles
Lee's well-known Vade-mecum.
448 E. A. MINCHIN ON SOME DETAILS IN THE ANATOMY OF
dissections if one is content to get out only the large meta-
thoracic ganglion-mass, in the thoracic series, and not to worry
about the ganglia of the first two thoracic segments, which
require very careful dissection.
A remarkable feature of the abdominal nervous system is that
it presents very marked differences in the two sexes of the flea.
These sexual differences are seen at a glance in the two figures
on PI. 26, which are drawn from two preparations to the same
scale by means of a camera lucida. At the upper end of each
figure we see the large metathoracic ganglion-mass, and at the
lower end the large hindmost or terminal ganglion-complex from
which nerves are given off to the genitalia. Between these two
larger nerve-centres at the two extremities there is a series of
smaller ganglia ; and it is easy to see that this series comprises
seven ganglia in the male and only six in the female.*
It is seen, then, that the male flea has one pair of ganglia
more in its abdominal nervous system than the female. Is this
an indication of superiority on the part of the male sex ? By
no means, rather the contrary ! In the embryonic development
of insects there are some ten or eleven pairs of abdominal ganglia,
and in the ontogenetic development, or in the phylogenetic
ovolution, of insects the tendency is for these ganglia to be
concentrated by fusion which takes place progressively from
behind forwards. In some of the Diptera — the tsetse-fly, for
example, and I believe in the common house-fly also — the
concentration of the nerve-ganglia has reached its maximum
possible, since the whole ventral chain is concentrated into one
large mass situated in the thorax, a mass which represents the
three pairs of thoracic ganglia plus the whole abdominal chain,
all telescoped forwards into one large ganglion-complex. In the
flea, however, the process of concentration and specialisation has
not gone so far, and is seen only at the hindmost end of the
* This curious point was discovered by Major Christophers, in his
dissections of fleas made in my laboratory. Previous to his work, I had
counted the ganglia of a female flea that I was dissecting, and had noted
that there were six small ganglia. Subsequently I made a mounted pre-
paration of the abdominal chain of a male flea, and was surprised to
observe seven small ganglia ; thinking I had made a mistake in my former
observation, I looked up my old notes and altered " six " to " seven, '
never suspecting the sexual differences which were subsequently shown to
exist.
THE RAT- FLEA, CERATOPIIYLLUS F ASCI ATI'S BOSC. 449
nervous system, in the large terminal ganglion-mass, which
represents a fusion of the most posterior ganglia. The difference
in the number of the abdominal ganglia in the two sexes of the
flea shows, therefore, that in the female the concentration has
gone one step farther than in the male, since only six abdominal
ganglia remain free in the female, but seven in the male. The
nervous system of the female has therefore reached one stage in
evolution higher in the female than in the male. Similar
differences between the sexes are known to occur also in other
insects, especially in the Hymenoptera (the order which includes
the bees, ants, and wasps), an order in which the superiority in
intelligence and in the social virtues of the female over the male
is very marked.
Besides the difference in the number of ganglia, the nervous
systems of the male and female flea differ also in the arrangement
of the nerve-stems given off from the hindmost ganglion-mass. In
the male two stout nerves are given off, which run on either side
of the " corkscrew-organ'' (see p. 454), and are distributed mainly
to the powerful muscles which work the penis. In the female,
however, three pairs of moderately stout nerves are given off,
which go to the genitalia, but I have not been able to trace their
exact distribution.
Comparing the two figures, it is seen that the male and female
nervous systems are approximately of the same absolute length.
Since, however, the female flea is considerably larger than the
male, the nervous system of the female is relatively much
the shorter, and does not extend so far into the abdomen as that
of the male. Consequently the nervous system of the male is
the easier to dissect out.
As regards minuter details, the nerve-ganglia are seen to
contain a number of nuclei, representing the ganglion-cells,
which have a bilaterally symmetrical arrangement, showing that
each ganglion-mass is a fusion of a pair of ganglia. The nerves
which come off from the ganglia right and left contain small,
elongated nuclei, which are the nuclei of the connective tissue-
sheaths of the nerves. The connectives running between the
successive abdominal ganglia contain no nuclei, but the stout
connectives passing forwards from the metathoracic ganglion-
mass contain elongated nuclei similar to those of the peripheral
nerves.
450 E. A. MINCHIN ON SOME DETAILS IN THE ANATOMY OF
II. The Salivary Glands.
Having occasion to dissect some flea-larvae, I was struck by
the fact that the salivary glands of the larva differ greatly, both
in size and in complication of parts, from those of the adult flea.
I will begin with the adult, in which the glands are both smaller
and simpler in structure.
In the adult flea the salivary glands lie in the abdomen, right
and left of the stomach, in the form of two tiny pouches on each
side (PI. 27, B and C). Each pouch consists of large glandular
cells, which tend to stain very opaquely and have large nuclei.
The two pouches of each side give off each a short duct, and these
two ducts unite into a long duct running forwards on the side of
the body to the anterior thoracic region, where the two ducts from
the two sides of the body unite into a common salivary duct, which
runs forwards to open, doubtless, into the hypopharynx, as in
other insects. The paired salivary ducts have a very character-
istic appearance, being lined by a chitinous cuticle which shows
internally a system of rather irregular transverse thickenings.
This appearance is seen from the point where the ducts issue
from the glands up to a short distance from the spot where the
paired ducts unite to form the common salivary, duct ; the
structure of the ducts recalls to some extent that of a tracheal
tube, but the transverse thickenings are not so perfectly regular
as in the tracheae. At the point of union of the right and left
salivary ducts, however, there is a Y-piece in which the duct
diminishes in calibre to about half, and has no transverse
thickenings. External to the chitinous lining, the duct is
covered by a delicate layer of flat epithelium, which does not
show distinct cell-outlines, but has the appearance of a plas-
modial or syncytial layer of protoplasm with scattered nuclei.
The salivary gland of the adult flea, on account of its small
size, is not so easy to dissect out ; the glands of the female are
slightly larger than those of the male. On the other hand, the
salivary glands of the larva, which are plainly visible through
the body-wall of the living insect, are very easily dissected out.
All that is necessary is to decapitate the larva in such a way as
to cut off the first or first two thoracic segments, together with
the head, and then to press with the flat of a dissecting needle
gently along the body from behind forwards, so as to squeeze out
THE RAT-FLEA, CERATOPHYLLUS FASCIATUS BOSC. 451
the contents of the body-cavity through the cut end of the trunk.
The salivary glands sometimes come out as soon as the flea is
decapitated, without any such pressure, and it is easy to get
them on to a cover-slip and fix them.
Almost the only point in which the larval glands (PI. 27, A)
resemble those of the adult is in the characteristic structure of
the duct, which can be recognised immediately. Passing back
along the duct (d.), we come to a thin- walled dilated sac or
reservoir (r.), quite absent in the adult. Behind the duct a
tubule begins, composed of lightly staining glandular cells. After
a short course this tubule becomes continuous with the gland
proper, which is composed of darkly staining glandular cells, and
branches out into three lobes or diverticula, two of which run
forward (l.a.1, l.a.2) and one backward (l.p.) alongside of the
digestive tract. All this arrangement of duct, reservoir, and
gland is, of course, duplicated on each side of the body, right
and left.
Accompanying the larval salivary gland are two elongated
pads or cushions of fat-body, which are very difficult to separate
from the gland without damaging the glandular lobes. In the
hinder of these pads of fat I found in many fleas a body which
looked exceedingly like a parasitic cyst, for which I mistook it at
first. Specimens mounted whole showed the " cyst " to be com-
posed of large cells in the interior, showing a. tendency in the
more advanced specimens to arrangement in longitudinal rows,
and enveloped by a layer of flat epithelium at the surface. At
its hinder end the " cyst " is prolonged into a delicate cord of cells
which could be traced in some specimens a long way back.
Further investigation showed, however, that when this " cyst "
was present on one side of the body it was also present on the
other side in exactly the same degree of development ; and further,
that when the "cysts" were absent in the fat-body on the level
of the salivary glands, they were to be found in other pads of fat-
body situated farther back, on the level of the intestine right
and left. Hence it was obvious that the supposed parasitic cysts
were simply the genital rudiments, situated farther forward in
the larvae of one sex than in the other. Whether it is the male,
or the female, in which they are situated farther forward, I
cannot say.
The striking differences between the larval and adult flea in
452 E. A. MINCHIN ON SOME DETAILS IN THE ANATOMY OF
respect to the salivary glands must be related to the difference in
their habits. The adult flea, I need not say, is a blood-sucker,
and in blood-sucking insects generally the function of the salivary
glands is believed to be that of producing a secretion which is
mixed with the ingested blood and prevents it from coagulating.
Incidentally the salivary glands of the adult flea, if crushed and
examined, can be seen to contain many yeast-like bodies of several
kinds, and it is supposed that it is these microbes which are
responsible for the local irritation and itching caused by the
puncture of the flea's proboscis. The flea-larva, on the other
hand, is more or less omnivorous, but appears to feed principally
on the faeces of the rat, as well as dirt and debris of all kinds.
Consequently its salivary glands have a function in the insect's
economy entirely different from that of the adult flea, assisting
probably in the digestion of the food, and their larger size in the
larva indicates a greater secretive activity than in the adult.
III. The Male Reproductive Organs.
The genitalia of the male flea exhibit a singular complication
of parts and of their arrangement, but are nevertheless very easy
to dissect out, and with a little care the entire reproductive system,
from testes to penis, can be mounted as one preparation, in which
every detail can be studied with the exception of those minuter
points of structure which require sections for exact study.
A general sketch of the various parts is given in Plate 28.
All the details of this sketch have been drawn from mounted
dissections with the camera lucida at a magnification of 150
diameters, reduced in the reproduction by one-half. At the same
time the relation of the various parts and their relative position
in the body has been checked by sketches of the whole system,
both of such parts of it as can be seen through the body-wall of
the flea without dissection, and also as it is seen when the abdomen
of the flea is freshly opened with the least possible disturbance of
the organs.
Most anteriorly are situated the two conspicuous testes (T , T.)
with their ducts coming off from them, and shaped somewhat like
a pear would be if the stalk (the duct) came off from its thicker
end. The testes lie dorsal to the stomach, but vary to some
extent both in size and arrangement. When the testes are of
large size, as in the younger males, they lie one in front of the
THE RAT-FLEA, CERATOPHYLLUS FASCIATUS BOSC. 453
other, and then the duct of the testis lying more anteriorly runs
straight back, while that of the testis situated more posteriorly is
coiled. When the testes are smaller, as in the older, more
exhausted males, they lie side by side and their ducts run straight
back.
When the testis is examined it is seen at once to consist of two
parts, a dilated bladder-like portion of ovoid shape, at the base of
which is a coiled tubular portion. The bladder-like portion
appears to be the testis proper (T ), while the coiled tubular
portion (ep.1) recalls the structure in the human testis known as
the epididymis, and may be known conveniently by this designa-
tion. In one of my dissections I succeeded in uncoiling the
epididymis forcibly, by pulling on the duct (ep.2). It was then
seen that the epididymis is a thin-walled tube, tilled with ripe
spermatozoa ; consequently, from the point of view of function,
the epididymis represents a vesicula seminalis, that is to say a
receptacle for the storage of ripe sperm.*
The calibre of the tubular epididymis narrows rapidly as it
passes on into the duct, which may be called here, as in other
animals, the vas deferens. The right and left vasa deferentia (v.d.1,
v.d.2) run back a little way and join to form the common vas
deferens (v.d.3), but it can be seen very easily that the union of
the paired vasa deferentia is merely external and not internal,
since the lumina, or internal cavities, of the two ducts remain
quite distinct.
The common vas deferens runs to a set of glandular structures
which I regard as corresponding to a prostate gland, and consist-
ing altogether of four blind tubular diverticula ; a median pair of
short tubules, which maybe termed the median prostates (r.m.p.),
and a much longer pair of lateral tubules, which may be called
the lateral prostates (r.l.p.). The two median prostates are in
close contact, but their cavities are quite distinct and independent.
The walls of the tubules are composed of a single layer of
glandular epithelial cells of small size, which show in surface view
very distinct polygonal outlines (PI. 30, B). The tubules contain
* The structure of the testis was not quite correctly described in our
monograph on the development of T. leicisi (Minchin and Thomson, I.e.).
When that was written I had not seen the epididymis uncoiled, and
regarded the dilated bladder-like portion of the testis as a vesicula
seminalis.
454 E. A. MINCHIN ON SOME DETAILS IN THE ANATOMY OF
a cavity, relatively spacious, in which I have never seen any
spermatozoa ; they cannot therefore be regarded as vesiculae
seminales, but probably have a purely secretive function.
The common vas deferens runs towards the median prostates
and then loops round them in a peculiar manner, running in the
valley between the two contiguous median prostates. Just after
the two still separate ducts, which form by their apposition the
common vas deferens, have passed the prostates, there is a slight
dilatation of the ducts into which the prostatic tubules open, but
quite separately ; that is to say, the left median and left lateral
prostate open into the left half, the right median and right
lateral prostate into the right half, of the common vas deferens.
The common vas deferens, after receiving the openings of the
prostates, runs on towards the penis as a duct which may be
termed, as in other animals, the ductus ejaculatorius (d.ej.).
Like the common vas deferens, however, the ductus ejaculatorius
is a double-barrelled structure, consisting of two ducts in close
contiguity, but with distinct internal cavities.
At the point where the ductus ejaculatorius enters the penis
there is a most singular complication of structure. The proximal
end of the penis is prolonged into a spirally coiled organ which,
for lack of a better name,* I propose to call the " corkscrew-
organ," since it resembles in form a corkscrew, or a spiral drill or
borer, of about four turns (c.s.o.). The ductus ejaculatorius runs
straight to the base of the corkscrew and through its axis ; at
the point where it enters the axis of the corkscrew the ductus
ejaculatorius can be seen very plainly to be still double ; it is
difficult to make out clearly what happens in the axis of the
corkscrew, but when this structure is viewed from the top, it is
seen equally plainly that the duct emerges from the axis as a
single duct, no longer double-barrelled. It is evident, therefore,
that the two ducts that come from the testes, maintaining their
individuality and distinctness up to this point, become confluent
at some spot in the axis of the screw. This single duct, the duct
* I regret to say that my meagre acquaintance, which I have not had the
leisure to extend, with the vast and scattered literature relating to the
anatomical structure of insects, is inadequate to permit me to state whether
this or similar organs in other insects have been studied in detail and
whether there exists already a special technical term for the structure
which I term here in a purely descriptive manner " corkscrew-organ."
THE RAT-FLEA, CBRATOPHTLLUS FASCIATUS BOSC. 455
"which runs the whole length of the penis, may be called dis-
tinctively the urethral duct (d.).* The exact point at which it
begins in the axis requires to be determined by sections.
The urethral duct emerges from the axis of the corkscrew at
its apex and there turns and runs outwards round the outer edge
of the spiral of the corkscrew, enclosed between two chitinised
bars, or more correctly thickenings of the wrall of the duct.
These chitinous thickenings are best seen in unstained prepara-
tions of the penis (PI. 29). The chitin on the inner side of the
duct (i.e. on the side of it turned towards the axis of the spiral)
is the thicker and stronger of the two, but is only continued
from the base over about three turns of the spiral, while the
thinner chitinous bar on the outer side of the duct is continued
for nearly a whole turn more.
The structure of the corkscrew -organ is difficult to make out
in full detail without sections, but if a portion of the spiral be
carefully examined, the following points can be seen in dissections
of the whole apparatus stained and mounted (PI. 30, A). At the
extreme outer edge of the spiral is seen the narrow urethral
duct (d.) with its chitinous thickenings on the inner and outer
side. Running from the axial region, which can also be seen in
the unstained preparations to have a chitinous support (ax.), is a
superficial layer of radiating striated muscles, which run across
from the axis centrally to the duct peripherally; this layer can be
focused without difficulty. At a deeper focus, below the radiating
muscles, two structures can be made out lying between the axis
and the duct ; close to the axis and apparently attached to it, is
a spiral muscle (sp.m.) composed also of striated muscular fibres ;
and between the spiral muscle and the urethral duct is a cushion
of cells which appear to be glandular in appearance, but sections
would be necessary to determine their precise histological nature.
These various structures can be seen best in the lowest coil of the
oorkscrew ; they are depicted in Plate 30, A, but it is difficult to
* If a dissection of the male reproductive organs be treated with caustic
potash, everything up to the base of the corkscrew, that is to say the vasa
deferentia, prostates and ductus ejaculatorius, dissolve away, but the
urethral duct issuing from the apex of the corkscrew remains very distinct
and this is, as a matter of fact, the best way to study its course. It would
appear, therefore, as if the urethral duct is distinguished from the other
ducts by the possession of a chitinous lining, and therefore represents, pro-
bably, an ingrowth of the outer integument in origin.
456 E. A. MINCHIN ON SOME DETAILS IN THE AK ATOMY OF
combine clearly in one sketch things seen in the microscopic
preparation at different foci.
Seen in life, that is to say in a freshly dissected flea, the cork-
screw-organ is usually performing peculiar pulsating movements,
which remind one to some extent of the movements of the hair-
spring of a watch, with the difference that the hairspring lies in.
one plane, while in the organ of the flea the axis of the spiral i&
prolonged vertically so that a form like a corkscrew results. It
is seen that in the living condition the corkscrew becomes alter-
nately first longer and narrower and then shorter and broader.
The elongation and narrowing of the corkscrew is doubtless
brought about by the contraction of the radiating superficial
muscles ; these in their turn are antagonised by the spiral muscle,
which by its contraction would tend naturally to make the cork-
screw shorter and broader.
As to the function of corkscrew- organ, I can only offer the
suggestion that it may act as a sort of sperm -pump. The move-
ments seen in the freshly dissected flea may perhaps become more
active and regularly rhythmical during the act of copulation,
and serve to pump the sperm on from the ductus ejaculatorius
and vasa deferentia into the penis. This is, of course, a mere
conjecture from the observed facts of its structure and activity.
If, on the other hand, the cushion of cells between the spiral
muscle and the duct be glandular in nature, the organ as a
whole must have other functions in addition to that of acting
as a pump.
The penis is an organ of complicated structure, which I will
deal with briefly ; PI. 29 shows what I have been able to make
out in preparations mounted unstained, or further cleared with
potash before mounting. The penis (P.), which is very large in
proportion to the size of the insect, is made up of strong thick
bars of chitin. It is worked mainly by strong protractor and
retractor muscles attached to a broad bar of chitin (b1), which is
a prolongation of the dorsal integument at the right and left
margins of the pygidium. The median retractor muscles (m.r.)
are attached distally to a prolongation of the dorsal side of the
penis, and the lateral retractors (l.r.m.) are attached to a bar (b2)
which arises from the ventral side of the penis; there are two such
bars, right and left, diverging from one another like aV; it is
clearly impossible that the penis could be protruded farther from
THE RAT- FLEA, CERATOPHYLLVS FASCIA TVS BOSC. 457
the body than the point of insertion of these bars (b2). I think
it probable that there are more muscles attached to b2 than
are seen in my figure, but have become torn away in the dis-
section. Both b1 and b2 can be seen clearly through the body-
wall in the uninjured flea. From the thick beam of chitin
which forms the dorsal part of the penis a lateral muscle (l.m.)
omes off, which is probably attached distally to the integument.
In one of my preparations treated with potash, spermatozoa*
could be seen very plainly in the interior of the urethral duct,
and they have been put into the figure on PI. 29 in order to
show the course of the duct. The spermatozoa (sp.z.) begin in the
lowest coil of the corkscrew -organ, where they show a peculiar
festoon-like arrangement. As the duct passes into the body of
the penis, the spermatozoa take on an arrangement in wavy
bundles and the calibre of the duct widens considerably, and
at the same time the spermatozoa show that the duct crosses over
the chitinous bar which forms the inner boundary of the duct in
the corkscrew-organ, and which has now become very much
thinner and more delicate, passing on to be merged into a much
thicker bar on the ventral side of the penis. Just a little
in front of the middle region of the penis the spermatozoa are
heaped up in a way that shows the duct to have become greatly
enlarged in calibre, but behind this point the spermatozoa dis-
appear altogether. In stained preparations it can be seen that
the penis has a superficial layer of muscles which appear to have
a criss-cross arrangement, and lie on the wall of the widened
spermatic duct, but they have not been put into the drawing, as
their exact position and arrangement are difficult to make out
clearly. The contraction of the superficial muscles would doubt-
less have the effect of contracting the lumen of the penis and
ejecting the sperm.
Such are the main points of the structure of this very com-
licated apparatus, so far as I have been able to make them out ;
but I think it probable that there are more minutiae to be
described, especially with regard to the structural details of the
penis and " corkscrew-organ."
IV. The Female Reproductive System.
As regards the primary sexual organs of the female sex, they
are of the usual insectan type, and can be dealt with briefly.
Journ. Q. M. C, Series II. — No 76. 32
458 E. A. MINCHIN ON SOME DETAILS IN THE ANATOMY OF
There is a pair of ovaries, lying symmetrically right and left in
the abdomen dorsal to the stomach. Each ovary consists of a
number of ovarian tubes or ovarioles ; usually four on each side,
but in one of my mounted preparations there are five ovarioles in
each ovary. The ovarioles are of the simplest type, composed of
successive egg-chambers, increasing progressively in size, without
special yolk-chambers. The ovarioles of each side unite into a
short paired oviduct, and the paired oviducts of the two sides
unite into a median unpaired oviduct, in which, probably, the
ovum is fertilised and subsequently becomes invested by a shell.
In addition to the ovaries and oviducts, which are very easy
to dissect out, there lies, ventral to the rectum, an organ found
in all fertile female insects, the receptaculum seminis, into which
the sperm is received at copulation and stored up in order to
fertilise the eggs as required. The receptaculum and its duct
are by no means difficult to dissect out and mount, and make a
singularly beautiful and fascinating microscopic preparation
(PI. 31). The duct is coiled up into a veritable labyrinth, and the
sole difficulty in the dissection is to uncoil it without breaking it.
The receptaculum itself (R.S.) is a chitinous capsule with a
brown, delicately sculptured, semi-transparent wall, and a peculiar
form. The main portion of the capsule, that portion from which
the duct arises, is roughly spherical in form. At one point, which
is distant from the origin of the duct by about one-third of the
circumference of the main chamber, an outgrowth or diverticulum
arises, forming a second chamber, which is horn -shaped, and
bends round the main chamber. The horn-shaped chamber is
connected, on its concave side, to the main chamber by a sheet of
striated muscle (m.r.s.). The contraction of these muscle-fibres
must clearly have the effect of approximating the horn-shaped
chamber to the main chamber, and at the point where the
horn-shaped chamber arises from the main chamber there is a
rim of chitin which appears to be softer than the rest of the wall,
forming a weaker spot which apparently serves as a hinge,
allowing the horn-shaped chamber to be moved slightly ; it is at
this spot that artificial deformations of the wall of the capsule
are often caused as the result of slight shrinkage when the
receptaculum is mounted in Canada balsam. The receptaculum
is usually packed with spermatozoa, which can be seen through
the wall of the capsule, but better still if the capsule be burst
TIIE RAT-FLEA, CERAT0PHTLLU8 FASCIATUS BOSC. 459
open by pressure under a cover-glass when freshly dissected out.
In one of my specimens the receptaculum is empty and contains
no spermatozoa ; this specimen is also the only one I have
succeeded in mounting in Canada balsam without any shrinkage
taking place in the hinge-region. This virgin receptaculum also
shows some structures in the interior, the nature of which I have
not been able to make out clearly, but which look rather like
prolongations of the duct into the interior of the main chamber.
Sections would be necessary, however, to determine the nature of
these internal arrangements, which are not visible in any of my
specimens that are filled with spermatozoa.
The duct of the receptaculum (d., d., d.) is of extraordinary
length, and just where it arises from the main chamber it is
surrounded by a cushion of deeply staining, closely packed cells
of glandular appearance (gl.c.), each shaped somewhat like an
Indian club. The duct itself has an irternal chitinous lining
secreted by an external epithelial layer, which is shallow and
contains small nuclei in great number but shows no distinct
cell-outlines. At its proximal end, immediately after it comes
through the glandular cushion already mentioned, the duct is
surrounded by a great number of rounded cells (gl.), which have
clear, lightly staining contents, and present also a glandular
appearance. The rounded cells are thickly clustered round the
proximal end of the duct, but as the duct is followed along in
a distal direction they diminish in number and gradually thin
out until, about half-way along the duct, they disappear
altogether, and the distal half of the duct consists only of the
chitinous lining and the epithelium with small nuclei.
As the duct approaches its termination it shows some peculiar
complications, forming what I propose to call the terminal organ
(T.O.). First of all there is a feeble imitation of the corkscrew-
organ in the shape of a broad expanded plate, apparently
chitinous, on one side of the duct, which performs a spiral
twist of one complete turn. The spiral portion passes on into
a short length of the duct, which has on one side a thickening
of the chitin to form a strong bar (c.b.), bent like a bow, which
is strung, so to speak, by a strong muscle of four or five fibres
(m.t.o.). I have not been able to determine exactly by dissection
where the duct finally opens, whether into the unpaired oviduct
or into a terminal genital vestibule or vulva ; sections, or
460 E. A. MINCHIN ON SOME DETAILS IN THE ANATOMY OF
perhaps specimens cleared in potash, would he necessary to
determine this point.
The spermatozoa live a very long time, as is well known, in
the receptaculum, and are used up gradually to fertilise the eggs
as they are laid. In the queen-bee it is known that the insect
lays fertile eggs for at least three years, and in some other
insects this length of time may be exceeded by a considerable
amount. The muscles seen in connection with the receptaculum
and its duct may be connected with the function of passing out
the spermatozoa. A contraction of the muscle connecting the
horn-shaped chamber of the receptaculum with the main chamber
would probably force some spermatozoa out into the duct. On
the other hand, a contraction of the " bowstring " muscle of the
terminal organ would bend the " bow," and so occlude the duct,
preventing anything from passing out. There does not seem to
be any apparatus for forcing the spermatozoa up the duct and
into the receptaculum, but this is effected probably during
copulation by the male intromittent organ — possibly by the
problematic " corkscrew-organ." The spermatozoa in the recep-
taculum must be kept alive a long time, and may be nourished
by the secretion of the glandular cushion round the origin of
the duct, while the rounded gland-cells on the duct may perform
some similar function for the spermatozoa during their passage
down the labyrinthine duct, the great length of which is difficult
to explain in a plausible manner. All these suggestions have,
however, only the value of more or less probable surmises.
In the tsetse-fly the receptaculum is a paired organ, and in
the gnat there are three receptacula, one median and two
paired. In that of the flea there is no sign of any double
structure.
V. Muscle-cells of Stellate Form in the Oesophagus of the Flea.
In some of our smear-preparations of teased flea -stomachs,
made in the course of our investigation into the development of
Trypanosoma lewisi, there were to be found occasionally specimens
of the flea's oesophagus, which adhered to the cover-glass after it
had been fixed with Maier's sublimate-alcohol mixture and
stained by Heidenhain's iron-haematoxylin method. In such
preparations it is easily seen that the oesophagus has a beautiful
THE RAT-FLEA, CBRATOPHYLLUS FASCIATUS BOSC -tG 1
and very delicate layer of muscular tissue, in the form of a
network (PI. 32, A, B and C). The individual muscle-cells
are branched like ganglion -cells, and their processes anastomose
to form the network. Some nodes of the network are formed
merely by the union of two or three such processes, while other
nodes are formed by the body of the cell, and contain the
cytoplasmic cell-body with a nucleus. The processes themselves
are transversely striated, and form the actual muscle-fibres. It
can be seen that at a cellular node of the network the striated
fibres pass right through the body of the cell and come out
on the other side, their striation and individuality becoming
slightly less distinct in their passage through the cytoplasm of
the cell.
Remembering that I had seen muscle-cells of a somewhat
similar type in the " crop " or " sucking stomach " of the tsetse-
fly, an organ which is morphologically a diverticulum of the
oesophagus, I made a preparation of the crop of a common
house-fly and found a musculature of a very similar type
(PI. 32, D, E). The main differences are, first, that the cells
are on a much larger scale of size, requiring lower powers of the
microscope for their study ; secondly, that the muscular network
has a definitely rectangular arrangement, those fibres which run
in certain directions being considerably thickened, and connected
with one another by delicate fibres running across at right
angles. In some parts the thickening of these longitudinal fibres
is much more marked than in others. All the fibres, even
the thinnest, show the characteristic transverse striation very
distinctly.
The resemblance of the muscular network in the two cases
raises some interesting points of phylogeny. In the first place,
it should be noted that a contractile network is the most
efficient arrangement for the contraction of a bladder, since it
gives an even contraction in all directions. The muscles of the
human urinary bladder are also arranged in a network, but on a
much larger scale than those described here, since the strands of
the network are not outgrowths of individual cells, but are made
up of thick bundles of contractile cells. It is therefore not
surprising to find a network in the contractile elements of an
organ such as the crop of the house-fly. On the other hand, it
is rather remarkable to find it in the oesophagus of the flea.
462 E. A. MINCHIN ON SOME DETAILS JN THE ANATOMY OF
Entomologists are generally agreed in regarding the fleas as
modified and specialised Diptera — that is to say, as descended
from fly-ancestors. If so, they may have once possessed a crop
such as is found in the fly, but which, with reduction in the size
of the body, has gradually disappeared, and has ceased to be
developed. Since, as has been pointed out, the crop is formed as
a diverticulum of the oesophagus, the existence of such an organ
in the ancestors of fleas might explain the persistence of a
musculature of this peculiar type in the oesophagus of the flea.
But it would be necessary to examine the oesophageal muscula-
ture of other insects before adopting this theory as an explana-
tion of the presence of stellate muscle-cells in the flea.
DESCRIPTION OF PLATES.
Plate 26.
Abdominal Nervous Systems of the Male (left) and
Female (right) Flea, magnified 90 Diameters.
th.3, metathoracic ganglion ; abd.1, abd.3, abd.5, and abd.6, first,
third, fifth, and sixth abdominal ganglia ; abd.7, 7th abdominal
ganglion, present in the male, wanting in the female ; T.g.,
terminal ganglion-complex. Note the difference in the size and
number of the nerves that arise from T.g. in each case.
Plate 27.
Salivary Glands of the Larval and Adult Flea.
A, salivary gland of the larva, magnified 60 linear ; d., duct,
showing at its distal extremity (to the right) the union with the
corresponding duct from the other side of the body ; a small
portion of the duct is seen magnified 400 linear; r., reservoir;
l.a.1 and l.a.2, the two anterior lobes of the gland ; l.p., the
posterior lobe.
B and C, the salivary glands of the adult flea, at B magnified
60 diameters, for comparison with A, at C magnified 160; d.,
duct ; gl., the two pouch-like glands.
the rat-flea, ceratophyllus fasciatus bosc. 463
Plate 28.
General View of the Reproductive Apparatus of the
Male Rat -flea, seen from the Right Side.
T, T, the two testes ; ep.1, the left epididymis in its natural
coil ; ep.2, the right epididymis forcibly uncoiled ; v.d.1, v.d.2, the
left and right paired vasa deferentia ; v.d.3, the common vas
deferens; r.l.p., the right lateral prostate gland; r.m.p., the
right median prostate ; d.ej., the ductus ejaculatorius ; c.s.o.,
the " corkscrew-organ " ; d., the urethral duct running spirally
round the corkscrew-organ; P, the penis. x 75 linear.
Plate 29.
Chitinous Skeleton and Principal Muscles of the Penis and
Corkscrew-organ of the Male Rat-flea, from the Left
Side.
P, penis; e.p., external plates of the posterior end of the body;
b.1, chitinous bar, an outgrowth of the dorsal integument ;
b.2, chitinous bar arising from the ventral-posterior end of the
penis; l.r.m., lateral retractor muscles running from b.1 to b.2 ;
m.r.in., median retractor muscle running from b.1 to an out-
growth of the dorsal side of the penis ; l.m., lateral muscle
running from the side of the penis to the body -wall; p.m., pro-
tractor muscle, running from b.1 to the penis; c.s.o., corkscrew-
organ ; ax., its axial skeleton ; d., the urethral duct ; sp.z., sp z.,
spermatozoa in the duct, indicating its course where the cork-
screw-organ passes into the penis, x 150 linear.
Plate 30.
Details of the Male Reproductive System more highly
magnified.
A, a portion of one of the coils of the "corkscrew-organ," seen
from the lower surface; d., the urethral duct, running at the
extreme outer edge of the spiral; ax., the chitinised axis of the
spiral; running from ax. to d. are the superficial radiating muscles,
clearly seen ; below the radiating muscles two structures are
464 E. A. MINCHIN ON THE RAT-FLEA, CERATOPHYLLUS FASCIATUS.
seen, less clearly ; close to ax. is a spiral muscle, sp.m. ; between
sp.m. and d. is a cushion of cells with nuclei, apparently glandular
in nature. x 350.
B, a portion of one of the prostatic tubules, in surface view,
showing an epithelium composed of glandular cells with very
distinct polygonal outlines, x 350.
Plate 31.
Accessory Reproductive Apparatus of the Female Rat-flea.
U.S., receptaculum seminis ; m.r.s., muscles connecting the
main chamber of the receptaculum with its horn-shaped pro-
longation ; gl.c, cushion of gland-cells surrounding the duct at
the point where it issues from the receptaculum ; d., d., d., the
long coiled duct of the receptaculum, seen here forcibly uncoiled;
gl., gland-cells, thickly crowded on the proximal part of the duct;
T.O., terminal organ; c.b., bar of thickened chitin on the wall of
the termination of the duct; m.t.o., "bowstring" muscle of
the terminal organ. The apparatus is seen at a magnification
of 200 linear ; at A and B are seen portions of the duct magnified
400 linear.
Plate 32.
Stellate Muscle -cells of the Oesophagus of the Flea
and the Crop of the House-fly.
A, oesophagus of the flea, magnified --0/-- linear, showing the
muscular network; B, a detail of A, magnified 1,000 ; C, a detail
from another specimen, magnified 1,000, showing how the striated
muscle-fibres are continued through the cytoplasm of the muscle-
cells.
D and E, muscular network from two different regions of the
crop of the house-fly ; both from the same specimen, and
magnified to the same degree as A.
Lister Institute,
January 'Z5th, 1915.
Journ. Qvekett Microscopical Club, Ser. 2, Vol. XII., No. 70, April 1915.
Journ. Q.M.C.
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465
THE PRESIDENT'S ADDRESS.
THE BIOLOGICAL CONCEPTION OF INDIVIDUALITY.
By Prof. Arthur Dendy, D.Sc, F.R.S.
{Delivered February 23rd, 1915.)
I need hardly remind you that the organic world, as we know it
to-day, is divided by systematic biologists, largely for their own
convenience and in accordance with their own particular ideas,
into some millions of different kinds or species of plants and
animals, and that each of these so-called species consists, usually
at any rate, of millions of units which we call individuals.
In making this statement we most of us probably think
that, whatever may be our doubts as regards species, we know
very well what we mean by the term "individual"; we can
recognise and define an individual man or dog, or an in-
dividual oak tree or cabbage, at any rate to our own
satisfaction. If, however, we carry our investigations a little
below the surface of things wre soon meet with cases that are
not a little puzzling, and my purpose this evening is to inquire,
albeit very briefly, whether it is really possible to frame a
definition of individuality from the biological standpoint that
will be of general applicability throughout the animal and
vegetable kingdoms ; whether we are really much better off in
this respect in dealing with individuals than we are in dealing
with species.
There appear to me to be two main paths by which we can
approach our problem, the morphological and the physiological.
On the one hand we can inquire what constitutes a perfect
individual from the point of view of structure, and, on the other,
what constitutes such an individual from the point of view of
function. In the case of the higher animals we might approach
the question in a third way and inquire what constitutes an
individual from the psychological standpoint. We shall find, as
we pursue our investigations, that each path is beset with
difficulties, and that each leads to some very curious situations.
We shall also discover that the three paths are not entirely
466 the president's address.
distinct, but frequently run together, and that the best going is
sometimes to be found along one and sometimes along another.
Starting along the morphological road Ave shall very soon find
that there are many grades or orders of individuality, and that
what constitutes a perfect individual in one case may by no
means do so in another.
Amongst the lower forms of life the individual frequently
consists, as you know, of a single cell, a single nucleated mass
of protoplasm capable of performing by itself all those actions or
functions which are necessary for the maintenance of life. The
cell is, of course, frequently looked upon as the lowest structural
unit, and the unicellular plants and animals as individuals of the
first order. It may fairly be questioned whether this view is
strictly correct, for the nucleated cell has already progressed a
long way along the path of evolution, and it is quite conceivable
that it may have originated as a colony of individuals of a still
lower order — micellae, plastidules, biophors, or whatever else we
like to call them ; while it is certain that some existing organisms,
such as the Bacteria, have not yet attained the level of perfect
cells.
We know, however, that all the higher organisms actually
start life as single nucleated cells, formed usually by the union of
two gametes or germ cells, and that these germ cells themselves
originate as complete nucleated cells by the process of cell-division,
and not, so far as we can tell, by the multiplication and addition
of units of a lower order. This fundamental fact seems to justify
us in looking upon the cell as the lowest morphological unit, and
we may accordingly accept it as the starting-point for our inquiry.
A unicellular organism, after attaining a certain size, and
under favourable circumstances, may divide into two parts which
completely separate from one another and form two new and
independent individuals. In this simple process of reproduction
the parent cell ceases to exist as an individual, but we cannot say
that it perishes, for its substance is merely divided between the
two daughter cells and there is nothing left over to die.
In the multicellular animals and plants we meet with a very
different state of things. Here the individual is composed, not
of a single cell, but of a number of such cells, often amounting to
very many millions, all united together in one body. Moreover,
these cells are not all alike, but very variously differentiated
THE PRESIDENTS ADDRESS. 467
amongst themselves for the fulfilment of different functions, and
all co-operate in a common life which is fuller and more varied
in accordance with the greater complexity of structure. This
differentiation and division of labour amongst the constituent
cells of the multicellular body has undoubtedly been one of the
chief means by which progressive evolution has been rendered
possible. From the point of view of the individual, however, it
has its drawbacks. Each cell is no longer self-sufficing, it can
no longer perform, by itself all the functions necessary for con-
tinued existence. A muscle cell, for example, is dependent upon
the blood for its supply of food and oxygen, upon the nervous
system for its means of communication with other parts of the
body, and upon the skin for its protection. It can do its own
particular job remarkably well, but only by sacrificing the power
to do other things that are very necessary for its own existence.
It has ceased to live as an independent individual and has become
a mere constituent part, an organ, of an individual of a higher
order. Moreover, it sooner or later loses the power of reproducing
itself by multiplication, becomes worn out and dies. So it is with
the vast majority of all the cells of which the multicellular body
is composed. They become worn out and die, and the body as a
whole perishes, death being the inevitable price paid for progress.
Certain cells in the body, however, escape the general debacle.
These are the germ cells, and the reason for their exemp-
tion seems to lie in the fact that they never become highly
specialised, never exhaust themselves by work, and never lose the
power of multiplication. They survive and start the game afresh.
They have been aptly compared to so many unicellular Protozoa
enclosed within the multicellular body — in it but not of it — and,
like the Protozoa, enjoying at least a potential immortality.
If we inquire how the multicellular condition arose from the
unicellular in the course of evolution we find an answer in two
directions. In the first place the existence of protozoon colonies —
especially such forms as Yolvox — shows us clearly the first step in
the transition, and in the second place we see the actual process
repeated with more or less accuracy in the development of all the
higher animals from the unicellular egg. The division of the egg
into embryonic cells or blastomeres in the process of segmentation
is exactly comparable with the multiplication of an amoeba by simple
fission. There is only one difference, and that is that the daughter
468 the president's address.
cells all remain together instead of separating. Somehow or other
they have learnt the value of co-operation. At the close of
segmentation, in a typical animal development such as that of a
sea urchin, or even of so highly organised a form as Amphioxus,
the embryonic cells arrange themselves in a form which exactly
reproduces the arrangement seen in a colony of Volvox, giving rise
to the blastula, a hollow spherical embryo with a wall composed
of a single layer of cells.
It seems fairly certain, from such considerations, that the origin
of all the higher animals is to be found in the habit, in which
so many Protozoa indulge, of forming colonies, and the particular
type of colony which has led to the best results appears to have
been that adopted by Volvox and by the radiolarian Sphaerozoum.
The branching type of colony, met with in the Vorticellidae and
many other groups, appears to have led to no important advance
in organisation, and we shall see presently that this holds true
also in the case of higher divisions of the animal kingdom.
The mere habit of colony formation is not, however, sufficient
to secure progress : there must also be differentiation and division
of labour amongst the constituent cells, so that the entire
organism may form a machine of greater efficiency in the
struggle for existence. In this process the individual cells
become mutually dependent upon one another — the whole
colony undergoes what is termed integration, and comes to form
a single individual of a higher order, an individual which cannot
be separated into its constituent parts without perishing.
In such forms as Sphaerozoum, Volvox, and the blastula stage
in the development of higher animals, the processes of differentia-
tion, division of labour and integration have not gone very far,
and such forms may still be regarded as mere colonies of single
cells. In the main line of evolution of the animal kingdom the
next step appears to have been the conversion of the hollow
spherical colony of Protozoa into the coelenterate type, a process
which is represented in every typical development by the conver-
sion of the blastula into the gastrula.
If we accept the familiar principle of the recapitulation of
ancestral history in individual development, we gain a very clear
idea as to how the coelenterate type probably arose. The hollow
sphere of one layer of cells became converted into a sac formed of
two layers, with a mouth at one end leading into a primitive
THE PRESIDENT'S ADDRESS. 469
digestive cavity. This process actually takes place in a variety
of ways in the development of different animals at the present
day, and we need not stop to inquire which of these ways
represents most closely the course originally followed in ancestral
history.
We have now arrived at a very definite type of multicellular
structure — the gastrula of embryologists — with a well-marked
differentiation of the constituent cells into two very distinct
groups with widely different functions — an outer protective layer
and an inner layer concerned in nutrition, known in embryonic
forms as epiblast and hypoblast, in adults as ectoderm and
endoderm respectively.
An organism possessing this type of structure has passed
definitely beyond the stage of a mere colony of Protozoa, and
constitutes what we may term an individual of the second order.
The best and most familiar example of such an individual is the
freshwater polype Hydra, which differs from an embryonic
gastrula in little more than the budding out of tentacles around
the mouth and a certain amount of histological differentiation
amongst the constituent cells of both ectoderm and endoderm.
The organism has now gained a fresh starting-point for further
evolution ; there is a new unit of a higher order with which
to build, and it is extremely interesting to see how the next
really great advance begins, just as it did amongst the Protozoa,
with colony formation.
Almost the only type of colony met with amongst the
Coelenterata, however, is the branching type, but the mode of
branching is extremely various. No great advance has been
attained in this way, though some of the colonies produced are of
much interest in discussing the problem of individuality. This
is especially true of the Siphonophora, those freely floating colonies
of Hydrozoa which form such an important constituent of the
oceanic plankton. In many of these we find differentiation
and division of labour amongst the constituent individuals
carried to such a high degree, and accompanied by so complete
an integration, that one is tempted to regard them as something
more than mere colonies, for in such integrated colonies the con-
stituent individuals tend to become converted into mere organs
subserving the welfare of the whole and quite incapable of
independent existence.
470 the president's address.
Take, for example, such a form as Nectalia or Physophora.
Here we have a large number of individuals or zooids attached
to a common stem. At the upper end a single modified in-
dividual forms a float. Along the length of the stalk two rows
of differently modified individuals form swimming bells, which
have concentrated their energies entirely upon the function of
locomotion, and have completely lost the power of feeding them-
selves and of reproducing their kind. At the bottom of the
stalk an expanded disc bears a number of other zooids. Some
of these have mouths and stomachs, and fishing tentacles
provided with thread cells, and their duty is to provide and
digest food, not only for themselves but for the entire colony.
Others, again, form protective shields or bracts, and yet others
bear the germ cells upon which the organism depends for
reproduction.
This is, clearly, a very highly organised type of colony.
Whether, indeed, we should still call it a colony or regard it as
an individual of the third order is a debatable question, and
one which is of no vital importance, for we must remember that
it is impossible to draw hard and fast lines across the path of
evolution and say that all on one side of a given line is one thing
and all on the other side something else.
At any rate, such colonies seem to have reached the limit of
their progress, and have not afforded any fresh starting-point
from which a new line of evolution has originated.
There are, however, certain other Hydrozoa which exhibit a
type of colony formation that seems to foreshadow higher possi-
bilities. I refer to the common jelly-fish known as Scyphomedusae.'
The hydroid phase of these organisms forms temporary colonies
by a process totally different from branching. The entire
hydroid divides transversely into a heap of little jelly-fish or
ephyrae, resembling a pile of saucers. These remain together
for a while and form a kind of colony known as a strobila, but
presently they all separate and swim away.
Amongst the coelenterates this process of strobilation is never
accompanied by any considerable differentiation and division of
labour amongst the constituent individuals of the colony, and
still less by integration, so that it leads to no higher type of
organisation. When we come to the worms, however, which
have undoubtedly arisen from coelenterate ancestors, we find in
THE PRESIDENT'S ADDRESS. 471
inany cases that the process of strobilation assumes much greater
importance, and finally leads to a new type of structure char-
acterised by what zoologists term metameric segmentation, or
serial metamerism. The earthworm is, of course, a typical
example of such a metamerically segmented animal, the body
consisting of a number of distinct segments or metameres arranged
in linear series one behind the other, and each one, to a certain
extent, repeating the structure of all the others, each with its
own division of the alimentary canal, its own division of the
vascular system, its own division of the excretory system, its own
division of the nervous system, and so on, but all united together
in mutual dependence and incapable of separate existence.
Differentiation and integration have, indeed, gone so far in
the case of the earthworm that we can no longer regard the
animal as a mere strobila or linear colony. It is undoubtedly a
single individual of the third order.
In some other groups of worms, however, the process of
integration has hardly commenced, and the different segments
sooner or later separate from one another as distinct individuals.
We see a good example of this in the Planarian Microstoma
lineare, where transverse division, frequently repeated, results in
the formation of a strobila or chain of perfect individuals that
only remain temporarily associated with one another. We see
something of the same sort in the tape- worm, which consists of
a chain of so-called proglottides attached to a head or scolex, and
each containing, amongst other things, a complete set of repro-
ductive organs.
Even in some of the highly organised chaetopod annelids, the
group to which the earthworm belongs, we sometimes find new
segments being added to the chain throughout life, by a kind of
linear budding or transverse division, and in many cases groups
of segments separate off from time to time as independent
individuals.
The earthworm, however, has lost the power of reproducing
independent individuals in this fashion. The process of integra-
tion has gone too far, for certain essential organs have become
restricted to special segments and separation into constituent
units is no longer possible.
The same phenomenon of metameric segmentation is exhibited
throughout the whole of the great group Arthropoda, which
472 the president's address.
indeed are in all probability descended from annelid ancestor
The common crayfish, for example, is made up of nineteen, or,
according to some authorities, twenty segments, each having its
own pair of limbs or appendages, all of which can be readily
derived from one and the same common type of structure. In
the arthropods, however, we find the process of integration
carried much farther than it is in the annelids. Any ordinary
insect, as you know, shows a well-marked differentiation into
head, thorax and abdomen, each of which is composed of a
number of segments which co-operate in the fulfilment of some
common function, or rather of many common functions. There
is not only differentiation and division of labour between individual
segments, but the segments are grouped so as to perform their
functions more advantageously.
It is precisely the same in the highest phylum of the animal
kingdom, the Vertebrata. These are all metamerically segmented
animals, derived in all probability from some metamerically
segmented, worm-like ancestral form. The process of integration
has gone so far, however, that but few indications are left,
externally at any rate, of their origin ; though we see abundant
traces of serial metamerism in their internal organisation, as for
example in the segmented vertebral column and the segmentally
arranged cranial and spinal nerves. In the early stages of develop-
ment the metameric segmentation is much more obvious and
cannot possibly be overlooked.
It may seem absurd enough to the layman to say that the
human head is made up of at least twelve segments, each of
which corresponds to a complete individual in some remote
ancestral linear colony, but the statement is in all probability
strictly true.
In the main line of evolution of the animal kingdom, then,
we can recognise three very distinct grades or orders of indi-
viduality from the morphological point of view. First, the single
cell, as in the Protozoa ; second, the simple multicellular type, as
in the Coelenterata and the majority of the flatworms, and
third, the metamerically segmented type, as in the annelid
worms, the arthropods and the vertebrates ; and each succeeding
higher grade has been derived from the one below it through the
process of colony formation, followed by differentiation, division
of labour and integration.
THE PRESIDENT'S ADDRESS. 473
From this point of view it is clearly impossible to establish
any definite criterion of individuality of general applicability, for
it is impossible to say exactly when a colony ceases to be a colony
and becomes an individual of a higher order. Our ideas of
individuality change completely as we review the animal kingdom
from the Protozoa upwards.
It might be supposed that some light would be thrown upon
our problem by the study of the development of the individual
from the egg, and this is certainly a very profitable line of inquiry.
Can we say that we mean by an individual the whole undivided
body into which the egg-cell develops 1 We certainly can in many
cases, but there are many other cases in which we just as certainly
cannot.
Let us return for a moment to the simple hydroid colony, as
we see it, for example, in Obelia or Sertularia. Here the fertilised
egg develops first into a single multicellular individual, but that
individual does not stop developing when it has attained its full
growth ; it branches out and produces other individuals by a pro-
cess of budding, and in the colony thus formed it is impossible to
say where one individual ends and another begins, though it may
be quite possible to tell how many individuals there are altogether
by simply counting heads. It is not, as a rule, until many non-
sexual individuals have been produced that some particular bud
develops into a new sexual individual which once more produces
eggs or sperm. Moreover, in this alternation of sexual and non-
sexual generations the two generations generally differ widely
from one another in structure, the sexual jelly-fish being strongly
contrasted with the non-sexual hydroid polype.
A similar phenomenon of alternation or metagenesis occurs, of
course, in many other animals and in all the higher plants,
usually accompanied by great multiplication of the non-sexual
generation by some process of budding. An ordinary tree is the
non-sexual generation, and we can get as many individuals out
of it as we like by taking buds or cuttings, though we are
accustomed to look upon the whole tree as a single individual.
A difficulty of quite a different kind is presented by the lichens,
which are well known to be composite organisms, made up of
combined algal and fungal constituents, and by the myxomycetes,
where the plasmodium is formed by the union of a number of
separate amoebulae. Here we get a number of individuals,
Journ. Q. M. C, Series II.— No. 76. 33
474 the president's address.
originally quite separate, and even of different parentage, com-
bining to form an individual of a higher order of quite a different
nature from any produced by ordinary colony formation.
Such mixed individuals are rare in a state of nature, but
various experiments show that they are quite easily produced
artificially in certain cases. We can make mixed or composite
individuals by the process of grafting both in plants and animals
It is by no means difficult to graft together parts of two hydras.
We can even join the hind part of one tadpole to the front part
of another, and the product may develop into a complete frog,
derived possibly from individuals of two distinct species.
Modern surgery has enabled us to perform marvellous grafting
operations even upon the human subject. A few years ago
an account was published of a girl whose knee-joint had been
removed and replaced by that of another person, with perfect
success. Theoretically, and apart from the difficulties of technique,
there seems to be no limit to the possibilities of surgery in this
direction. It would almost seem as if the whole organism were
made up of a number of interchangeable standard parts, like a
bicycle. Suppose it were possible to carry on the process until
all the parts of the body had one by one been replaced by others,
what would be the result from the point of view of individuality ?
Should we be able to say that the same individual still existed
after all the operations had been carried through ? It reminds
us of the Irishman's knife, that at various times had had all
the blades replaced and a new handle, but was still to him the
same knife.
Other experiments have shown that it is possible to produce
mixed individuals by joining together embryonic cells or blasto-
meres derived from different eggs. Garbowski in 1904 succeeded
in uniting blastomeres derived from different embryos of a sea-
urchin, either by hydraulic pressure or by squeezing them
together by means of glass-headed pins. The fragments of the
divided embryos were coloured intravitally with various stains
that did not injure them, so that they could be readily distin-
guished from one another. Even when the blastomeres were
taken from embryos in different stages of development, the
composite embryos formed from their union developed into
uniform pluteus larvae by means of various regulation processes.
An American biologist, H. V. Wilson, has shown that if a
THK PRESIDENT'S ADDRESS. 475
hydroid colony, such as Eudendrium or Pennaria, be cut up
into small pieces and then squeezed through fine silk gauze,
it is reduced to a kind of cream or pulp in which the constituent
cells are more or less completely separated from one another. If
kept under suitable conditions, however, in pure sea-water, the
separate cells join together again in irregular assemblages,
to which Wilson has given the name " restitution masses,"
and such a restitution mass may behave like an embryo and
develop into a new hydroid colony. The cells arrange themselves
in the proper layers, ectoderm and endoderm ; the ectoderm
secretes a new horny perisarc, branches grow out, and finally
new hydroid polyps are produced at the ends of the branches.
It is impossible in such a case to formulate any definite
relations between the component individuals of the original
colony and those of the new colony developed from the restitution
mass. The whole thing was simply pulped, and the separated
cells apparently reduced to an indifferent condition with powers
of fresh association in new combinations, while many of the
original cells seem to be used simply as food-material for the
new colony.
This experiment is to some extent paralleled by what takes
place normally in the development of the gemmules of the
freshwater sponge. A number of wandering amoebocytes,
charged with food-yolk, migrate to one spot in the parent
sponge, and there become enclosed in the characteristic capsule
secreted by surrounding cells. On germination the capsule is
ruptured, and an amoeboid mass creeps out ; the constituent
cells behave like the blastomeres of an ordinary embryo, multiply
rapidly and become differentiated into the various tissue cells,
which arrange themselves in the manner characteristic of
the adult.
Such phenomena certainly suggest the existence of some directive
influence which enables the separate parts to co-operate in the
formation of a whole individual, but what is the nature of this
directive influence and where it is located are complete mysteries.
We have now inquired, so far as time permits, into the
question whether or not it is possible from the morphological
point of view to give any definition of individuality of general
applicability. We have seen that in the course of evolution
individuals of a lower order have given rise to individuals of a
476 the president's address.
higher order through the process of colony formation and integra-
tion, and that it is quite impossible to draw hard and fast lines
between the successive terms of the series. We have seen also
that even amongst highly organised plants and animals individua-
lity does not depend upon the preservation of the same identical
parts in the same association. Individuals may be subdivided
and joined together in a variety of ways, and parts of different
individuals may be interchanged without impairing their vitality.
In short, we can by no means frame a general morphological
definition of individuality.
Are we any better off* when we ask what constitutes an
individual from the physiological standpoint ? A criterion of
individuality is indeed often sought in the power to perform all
the essential vital functions, or, in other words, to live a com-
pletely independent life. A unicellular organism does everything
for itself. It feeds, respires, gets rid of its waste products and so
forth, all in a very simple but at the same time efficient manner.
A single cell of one of the higher plants or animals, on the other
hand, though it may live independently for some time in a
suitable medium, cannot do so indefinitely. It has sacrificed the
power of doing everything for itself to the power of doing some
one particular thing more efficiently, and depends for its con-
tinued existence upon the co-operation of innumerable other
cells. Similarly, a single highly specialised individual of a
siphonophoran colony, such as a swimming bell of Physophora,
is quite incapable of independent existence ; from the physio-
logical point of view the colony as a whole constitutes the
individual, though the morphologist has little difficulty in
recognising the component members.
This leads us to the consideration of certain other cases of
great interest. Many of the higher animals, though they do
not form colonies in the morphological sense, have the habit of
living together in social communities which we might regard as
colonies of completely separated individuals. The honey bee is
a familiar example. In a hive of bees we find individuals of
three kinds, easily distinguishable from one another both by
habits and by structural peculiarities. The queen is a perfect
female, and is alone capable of laying eggs. The ordinary
workers are imperfect females which have sacrificed the power
of reproduction and concentrate their energies upon the collection
THE PRESIDENT'S ADDRESS. 477
of food and other important services necessary for the welfare of
the community as a whole. The drones are males j they do
no ordinary work, their sole function being to fertilise the queen.
None of these different kinds of individuals could live a really
independent life ; they are all mutually dependent upon one
another. The morphologist, however, would not hesitate to
regard them all as separate individuals, and I suppose the
physiologist would probably agree with him. But, if we are to
be strictly logical, from the physiological point of view the
complete individual can be nothing less than the entire community.
From this point of view, indeed, such communities might be
looked upon as individuals of yet a fourth order, but in which,
from the nature of the case, morphological integration is no
longer possible. It is much the same with human societies, in
which the component individuals become more and more dependent
upon one another as civilisation progresses.
But, you may say, there can at least be no doubt about
the individuality of my own self. I have my own personality,
complete and indivisible. Here we approach the psychological
aspect of our problem, into which I do not propose to enter.
I have no doubt, however, that the psychologist would tell
us that perhaps, after all, we may be mistaken in supposing
that we can attain a sharply defined conception of individuality
even in his province. Remarkable but, fortunately, abnormal
cases are well known, in which two or more personalities
alternate with one another in the life of what, from both the
morphological and physiological points of view, we unhesi-
tatingly call a single individual.
It appears, then, to be a hopeless task to seek for any
biological criterion of individuality that can be applied to more
than a very limited number of cases. We have constantly
to modify our ideas on the subject as we pass from one group
of organisms to another, and everything depends upon the point
of view. It is certain, however, that, whatever else an in-
dividual may be, it is something which works as a whole
for its own self-preservation and self-expression, and is more
or less antagonistic towards other individuals with which it
comes into relation in the struggle for existence.
Other facts that emerge quite clearly from our inquiry
are that co-operation, differentiation, division of labour and
478 the president's address.
integration amongst individuals of successively higher orders
constitute some of the most important factors by means of which
organic evolution is carried on, and that at each successive stage
of progressive integration a new individuality is acquired, the
organism entering into possession of new attributes that are
something very much more than the mere sum of the attributes
possessed by its constituent units.
Individuality, though a very real phenomenon, is a very
elusive one, and one which perhaps lies outside the legitimate
domain of the biologist. We can do little more than collect
the remarkable facts that confront us so frequently in the course
of our investigations, and hand them over to the philosophers
to deal with as best they can. How far the philosophers will
agree that progressive evolution consists to a very large extent
in the gradual merging of individualities of a_ lower order in
others of a higher order I do not know, but to myself as
a biologist this generalisation appears to hold a large measure
of truth.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 76, April 1915.
479
BRITISH HYDRACARINA: THE GENUS LEBERTIA.
By W. Williamson, F.R.S.E., and Charles D. Soar,
F.L.S., F.R.M.S.
{Bead March 23rd, 1915.)
Plates 33-34.
In his posthumous memoir published in 1879, under the title of
" Description de quelques especes nouvelles d'Hydrachnides du
Lac Leman," * Lebert described a hydracarid which he con-
sidered to be new on account of the form of its genital area.
He gave it the name of Pachygaster tau-insignitus, and he
explained the specific name by referring to the resemblance
which the light dorsal marking bore to the Greek letter tau (t).
As to why he selected Pachygaster as a generic name, he has
left us in the dark. The selection, however, was not a happy
one, as Meigen used it in 1803 (Diptera), Germar in 1817
(Coleoptera) and Gray in 1840 (Echinodermata).f In the year
following the publication of Lebert's memoir, Neuman changed
the generic name to Lebertia. % One can without difficulty
comprehend how, from the lack of detail, several species were
identified as tau-insignitus ; and although some few species were
described by Koenike and Piersig, it was not until after Sig
Thor's exhaustive study of the genus that its comprehensive
character was recognised. The result was, that although
tau-insignitus had been naturally designated as type, the working
out of the species which had been identified as tau-insignitus led
to the creation of other species, so that, curiously enough, tau-
insignitus was worked out of existence altogether. Sig Thor
apparently recognised the illogical position which had arisen, for
we find that later on he, in company with the late Prof. Forel,
examined the locality at Morges where Lebert had obtained his
specimens at a depth of 25 m. They were successful there in
obtaining material which proved on examination to be quite
distinct from anything previously described. As other repre-
sentatives of the genus were not met with, one may conclude
* Bull. Soc. Vaud., xvi. 327-377.
■f Nomen. Zool. Agassiz.
% Kgl. Sv. Vet. Akad. Handl., xvii. (3) 68.
480 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
with Thor that he and Lebert had obtained the same species in
the restricted area. But in re-establishing the species, Sig Thor
overlooked the fact that it had been previously designated as
type, and consequently we find that the original genotype and
the type of the sub -genus to which the genotype belongs are not
the same species. Further we find that the sub-genus containing
the genotype bears a different name from the genus, but one feels
sure that the rules laid down for guidance in such cases by the
International Zoological Congresses have been overlooked by the
indefatigable Norwegian acarologist not by design, but purely by
accident. To this we shall revert later.
A more troublesome matter, however, is the consideration of
two of Koch's species as members of the genus Lebertia, viz.
Hygrobates iconicus C. L. Koch, and H. inaequalis 0. L. Koch,
the former as a doubtful species, the latter as valid. These are
represented in Koch's Deutschlands Crustaceen, Myriapoden und
Arachniden in Heft 11-22/23 and Heft 11-20/21 respectively.
As Koch's work is not to be found in many of our libraries, it
will not be out of place to reproduce here Koch's descriptions of
the above species ; and as these can be taken as typical of the
descriptions in Koch's great work, workers who have not hitherto
had access to it will comprehend something of the difficulty
attending the identification of many of Koch's species, difficulties
which, moreover, are not rendered more easy of solution by his
figures of species.
11. 22 foem., 23 mas.
Hygrobates iconicus.
H. subglobosus, Jlavus, nigro-pictus, pedibus ciliis nullis.
Gross, fast kreisrund, doch ein wenig langer als breit, gewolbt,
glanzlos, zwei grosse Griibchen hinten an dem Mittelfleck, zwei
auf dem Riieken des Hinterleibs,. das Bruststiick vorn in zwei
Zahne verl'angert. Die Taster massig lang, ohne Auszeichnung.
Die Beine diinn, die vordern kurz, kaum so lang als die
Korperbreite, die hintern langer, alle kurzborstig, ohne
Schwimmhaare.
Gelb, die Flecken braunschwarz oder schwarz : die Mittelfleck
kurz, fast von der Gestalt eines Quadrats ; die Seitenflecken bis
zum Auge ziehend, breit, nicht lang. Die Riickenstreifen mit
THE GENUS LEBERTIA. 481
dem Winkelflecken zusammenhangend, zusammen genommen
zwei stark zackige Bander vorstellend : der nach diesen Bandern
seitwarts gezackte Gabelstreif heller gelb. Unten die Grundfarbe
wie oben, die Zackenstreifen von oben durchscheinend, aber weiter
von einander und in die Brust ziehend. Taster und Beine ocher
gelblich, meistens etwas aufs erdgriine ziehend.
Das M'annchen ist kaum halb so gross als das Weibchen,
meistens heller gef'arbt, und der zackige Gabelstreif breiter, die
Zackenstreifen aber schm'aler.
Variirt ubrigens mannichfaltig, so dass Vorder- und Hinter-
leibsflecken zusammen fliessen, die ganze Riickenflache schwarz
farben und nur eine sehr schmale Spur des Gabelstreifs iibrig
lassen. Die Farbe der Beine verdunkelt sich bis zum schwarzlich
grunen.
In dem Wiesengraben bei Zweibriicken im Monat Juli, nicht
selten.
11. 20 mas., 21 foem.
Hygrobates inaequalis.
H. aurantiacus, furca angusta albida, maculis omnibus con-
junctis, olivaceis, utrinque lobatis, pedibus breviusculis glaucis.
Kaum mittelgross, kurz eiformig, der Riicken gewblbt, glanzend,
mit sechs Griibchen, zwei beiderseits hinten am Mittelfleck, die
zwei hintern davon von einander entfernter, die zwei des Hinter-
leibs auf der Mitte des Riickens einander mehr gen'ahert ; das
Bruststuek flach, stark vorstehend, beiderseits der Taster in
eine scharfe Spitze verlangert. Die Taster ziemlich lang, diinn,
die Beine aber st'ammig, ziemlich lang, mit beweglichen biischel-
f brmigen Schwimmharchen an den vier Hinterbeinen.
Der Korper blass orangegelb, zuweilen auch ziemlich sattfarbig,
Seiten- und Riickenflecken zusammengeflossen, ;olivengriin, mit
hellern Punkten und Fleckchen, meistens aber zwei grovsse seit-
warts lappige Ruckenfelder vorstellend ; der Gabelstreif schmal,
kurzarmig, mit zwei Eckchen auf dem Riicken ; der Mittelfleck
zuweilen aufs rostrbthliche ziehend, entweder nur hinten durch
eine feine Linie mit den Seiten flecken verbunden oder frei. Die
Unterseite des Korpers gelblich, griin angelaufen, mit einem
olivengriinen Schatten an den Hiiften und einem Schattenstreif
auf der Mitte. Bruststiick, Taster und Beine bl'aulich griin.
482 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
Das Mannchen ist nicht halb so gross als das Weibchen, hat
mehr zusammengefiossene Riickenflecken und stets einen rost-
braunen Mittelfleck des Vorderleibs ; die Unterseite ist dunkler
griin iiberlaufen und der durchscheinende Mittelfleck auf der
Brust rbthlich sichtbar. Bruststiick, Taster und Beine sind
heller und weniger stammig. Am Hinterrande beiderseits ein
Eindruck.
Variirt ins blassfarbige ; bei sehr hellfarbigen Exemplaren
fehlen die hintern Flecken und alsdann erscheint das hintere
Drittel des Kbrpers durchsichtig weisslich.
Im Schwarzbach bei Zweibriicken in Rheinbayern sehr
gemein.
It will be seen at once that Koch makes much of colour and
of the shape of the colour patches, and as these, as Koch himself
admits, are variable, dependence placed on them for identification
is apt to lead to confusion. Nor do the scrappy structural
details bring us any nearer a decision as to what precisely is.
intended. Some colour is lent to Sig Thor's contention that
these are Lebertiad species in respect that iconicus is rough
skinned (glanzlos), has no swimming hairs and has the epimera
(Bruststiick) produced into two sharp teeth, one on each side of
the palpi. Inaequalis is smooth skinned, has swimming hairs
and has the epimera as in iconicus. The first may belong to
sub-genus Lebertia ( = Neolebertia Sig Thor) or to Pseudolebertia.
The second may be, as Thor has placed it, a Pilolebertia species.
If we turn to Koch's figures, we observe that iconicus (fig. 23) alone
represents the palpi with the long hairs so characteristic of the
genus Lebertia, though not in any detail, merely indicating the
existence of such. The ground is so uncertain that Thor admits
with respect to iconicus that exact identification is out of the
question and that the most that can be done is to record it as
Lebertia iconica (C. L. Koch) sp. dub.
With regard to inaequalis, Thor admits the difficulty in
deciding that figs. 20 and 21 represent the same species. If
we consider what appears to represent the natural size of each,
we are led rather to the view that instead of a male, fig. 20
represents a young nymph, which would probably account for
the absence of swimming hairs on the second pair of legs. These
are shown distinctly on the second pair of legs in fig. 21, though
THE GENUS LEBBRTIA. 483
the text only refers to swimming hairs on the two posterior pairs.
Based on the capture of specimens of Lebertia at Zweibriicken
(Koch's locality), which Thor believes to be identical with Koch's
species, Thor has redescribed the species as Lebertia inaequalis
(Koch, 1837) Sig Thor, 1900. This has been acknowledged as
valid by Continental writers, for records have appeared since
then from Switzerland, Italy and even from Turkestan.
As to the grouping of the component genera of the Hydra-
carina, various suggestions have been made. These have been
discussed by Wolcott in his Review of the Water Mites* In
his classification he groups Nilotonia, Lebertia, Oxus, Frontipoda,
and Gnaphiscus as sub-family Lebertiinae. In Koenike's later
classification f the sub-family Lebertiinae covers the last four
of these genera, Nilotonia being transferred to another sub-
family. Thor's Prodromus,% published in 1900, included several
other genera in addition to those noted by Koenike, and these
Thor designated as Family Lebertiidae. The Prodromus does
not discuss the matter, and owing to this want it does not appear
to have obtained favour among acarologists. Probably Koenike's
classification may be found to represent more closely than
hitherto the natural grouping of the genera, but until we know
more of the larval forms a definite expression of opinion must be
postponed.
Sig Thor makes some interesting reflections on the phylogeny
of Lebertia. In the absence of a sufficient knowledge of the
larvae, he has had recourse to the nymphal forms in conjunction
with the imagines for clues as to what course the line of descent
might take. He conceives a hypothetical form Urolebertia, from
which spring two other hypothetical forms, Protoxus and Proto-
lebertia — the former leading up to Gnaphiscus, Oxus and Fronti-
poda, and the latter to the sub-genera of Lebertia. Of these,
Pseudolebertia, Hexalebertia and Mixolebertia are the three
branches which have a common hypothetical ancestor in
Protolehertia. Descent is continued into Pilolebertia and Lebertia
( = Neolebertia), the former appearing to have qualities which
may be designated as of a dominant and the latter of a recessive
type.
* Trans. Amer. Micro. Soc., xxvi. 205.
f Abh. Nat. ver. Bremen, xx. 144.
% Nyt. Mag. / 'or Nature., xxxviii. (3), 263-266.
484 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
Sig Thor's exhaustive study of Lebertia has shown that the
genus can be resolved into two groups covering five sub-genera.
In the first group the skin is dotted over with fine pores, and
may be described as smooth, as it is without the papillae or
ridges found in the second group. Swimming hairs are always
present, though in rare cases these may be rudimentary. The
spines on the extensor surface of the first segment of the fourth
pair of legs also appear to lend themselves towards the dis-
crimination of the groups, as the second group may have from
five to ten, while the first group only has three or four, though
L. obscura forms a slight exception, as it has five or six.
Two sub-genera, Lebertia (Sig Thor's Neolebertia) and Pilo-
lebertia, belong to the first or smooth-skinned group, and these
may be contrasted as follows :
In sub -genus Lebertia the body is rather elongate. The
second pair of legs is without swimming hairs, while the third
and fourth pairs have only isolated ones on the fourth and fifth
segments. The number of these swimming hairs on each segment
varies — may, indeed, even be wanting — but does not exceed four.
It may be remarked here that in L. subtilis the swimming hairs
appear to be entirely wanting. The third and fourth segments
of the palpi are each fairly uniform throughout their length.
The third segment has on its inner surface five long bristles ;
three of these are distal, the middle one being fairly close to that
at the edge of the extensor surface. The fine pores on the flexor
surface of the fifth segment are not very distinct, while the few
small hairs on the extensor surface are entirely clustered at the
distal end, one or two isolated ones being placed rather farther
back. By Article 9 of the International Rules of Zoological
Nomenclature (1905) Neolebertia is suppressed in favour of
Lebertia as the name of the sub-genus.
In sub-genus Pilolebertia the body varies from oval to nearly
circular in outline. The second, third and fourth pairs of legs
have numerous swimming hairs. Contrasted with sub-genus
Lebertia, the third segment of the palpi is more like an inverted
cone, while the fourth segment is rather curved. The inner
surface of the third segment has also five bristles ; three of these
are distal, the middle one being distant from the edge of the
extensor surface, not close to it as in Lebertia. The flexor
surface of the fourth segment has two distinct pores well
THE GENUS LEBERTIA. 485
separated, while all the small hairs on the extensor surface are
distal.
In the second group the skin is either not dotted over with fine
pores, or, where such are present, they are indistinctly seen ; but
a more distinctive feature is the presence of papillae or of ridges
varying in length. Species which are apparently smooth-skinned,
but belong to this group, may be distinguished from the preceding
group by the presence of six long bristles on the third segment of
the palpi instead of five. As a rule, swimming hairs are either
quite rudimentary or entirely wanting, but in some species, e.g.
those with six bristles on the third segment of palpi, they are to
be found.
Three sub -genera, Mixolebertia, Pseudolebertia and Hexalebertia,
belong to this group.
In sub-genus Mixolebertia the skin may be papillose or finely
granular, finely porose, rarely smooth. Swimming hairs are
generally present. The inner surface of the third segment of the
palpi possesses six long bristles, while as many as ten spines
may be found on the extensor surface of the first segment of the
fourth pair of legs.
Pseudolebertia and Hexalebertia have certain characters
in common, in that they possess a skin which is apparently not
porose, but is coarsely papillated or covered with ridges of vary-
ing length, and that they are devoid of swimming hairs ; but
otherwise they may be contrasted as follows :
In sub-genus Pseudolebertia the third segment of the palpi
has five long bristles, of which three are towards the distal
extremity. One or two — more rarely three — of the fine hairs
on the extensor surface of the fourth segment are more proximal
than the others. The anal aperture is devoid of an outer
chitinous ring.
In sub-genus Hexalebertia the third segment of the palpi has
six long bristles. The fine hairs on the extensor surface of the
fourth segment are grouped about the distal extremity. The
accessory claw and lamina at the distal end of the sixth segment
of each leg are sometimes reduced in size. Anal aperture
surrounded by a chitinous ring.
Fortunately material was available to enable Sig Thor to work
out the nymphal characteristics of the sub-genera.
In sub-genus Pilolebertia, the nymph has a very finely
486 W. WILLIAxMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
ribbed skin dotted with fine pores. The epimeral area is rela-
tively broad, with the provisional genital area lying well within
the genital bay. The two long bristles on the extensor surface
of the third segment of the palpi are distal, as well as the small
hairs on the extensor surface of the fourth segment.
Sub-genus Lebertia also has a finely ribbed skin, dotted with
fine pores, but the epimeral area is relatively narrower and
longer, while the provisional genital area is set well back,
sometimes quite outside of the genital bay. Of the two bristles
on the extensor surface of the third segment of the palpi, one is
about the middle of the segment and the other distal.
Sub-genus Mixolebertia has the skin strongly ridged and three
bristles on the third segment of the palpi.
Sub-genus Pseudolebertia has the skin ridged, but more
sparingly than in the imago. The third segment of the palpi
has only two long bristles.
Sub-genus Hexalebertia has the skin similar to Pseudolebertia,
but the third segment of the palpi has three long bristles, one of
these being much more proximal than the others.
Sig Thor has also proposed to establish the sub-genus Duro-
lebertia to cover L. solida, but as that species appears to rest
on material hot too well preserved, the validity of Durolebertia
must remain open until further material is available to prove
its claims.
It may be here observed that American writers do not appear
to favour subdivisions as outlined above.
As the long bristles on the third segment of the palpi are an
important feature in the imago, the position of these on the
type species of the sub-genera may be approximately represented
as follows :
<
Lebertia. Pilolebertia. Mixolebertia. Pseudolebertia. Hexalebertia.
L. tau-inslgnita. L. insignis. L. brevipora. L. glabra. L. stigmatifera.
• ••• ••• ••• ••• •••
• • • •
• • •
THE GENUS LEBERTIA. 487
Between seventy and eighty species with varieties have been
described. The species described here, in addition to the sub-
generic types (excluding brevipora), are those found within the
Britannic area.
In dealing with the appendages of the body, it is generally
found convenient to designate the segments by number, the first
being invariably that which is articulated to the body. No
terminology has yet been agreed on, though Soar * and Koenike t
have discussed the matter.
Lebertia tau-insignita (Lebert) Sig Thor.
(Sub -gen. Lebertia.)
1879. Pachygaster tau-ivsignitus, Lebert, Bull. Soc. Vaud., xvi. 371.
1905. Lebertia tau-insignita (Lebert) Sig Thor, Zool. Anz., xxix.
52-59, figs. 18-24.
This species, which has been redescribed by Thor, has, so far
as known at present, a restricted range, being only recorded
from the neighbourhood of Morges on the Lake of Geneva. It
is the type species, and its inclusion here is therefore appropriate.
Thor describes the body outline as resembling a long ellipse,
whose length may vary from O90 mm. to l-40 mm. The
greatest breadth ranges from 0*80 mm. to l-05 mm. The venter
is weakly arched, the dorsum more strongly so. The anterior
margin of the body between the antenniform bristles is rounded,
or blunted. In this it differs from L. fimbriata, which Thor
selected as type of the sub-genus to which both species belong,
as well as with regard to the extent to which the anterior
extremities of the second pair of epimera extend beyond the
body margin ; in the case of the present species they do not
extend much. The skin is smooth and very finely porose.
Sometimes, particularly in young specimens, the skin has an
extremely fine striate appearance, due to the presence of very
fine folds. These are in no way comparable to the coarse
ridging of the skin such as may be observed in the sub-genus
Pseudolebertia, but Thor's view is that they are provision for the
increase in size of the body, since they become obliterated as
growth proceeds. The colouring is unusual ; it is almost entirely
blackish, with a semi-transparent yellowish zone round the edge
* Trans. Edin. Field Nat., v. 375.
f Ahh. Nat. ver. Bremen, xx. 158.
488 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
of the body. On the dorsum is the yellow fam-shaped (r) figure
indicating the organ variously designated as the excretory organ
and as the Malpighian vessel. The dark colour of the venter is
relieved by white and yellow specks. The legs are transparent
and tinged with green. Thor points out to what extent the colour
of the body responds to various preservative solutions, and the
necessity for caution in identification of preserved material in
those cases where colour may be of some value in assisting
identification. The palpi range from 0*40 mm. to 0*55 mm. in
length, and are more slender than the first pair of legs. The
second, third and fourth segments are covered with fine pores
clustered together in groups, which are distributed fairly evenly
over the segments. The bristles and hairs found distributed
over the segments appear to be fairly constant in the sub-genus
to which our species belongs. The first segment has only one
slightly curved bristle at the distal extremity of the extensor
surface. The second segment has three similar ones about
the middle of the extensor surface, and at the distal extremity,
but just towards the inner side, two long hairs about as
long as the third segment. The long bristle at the distal end
of the ventral or flexor surface is about as long as the segment
itself, and is minutely pectinate. The third segment has five
bristles, two about the middle, close to the extensor surface, and
three extremely finely pectinate ones at the distal inner sur-
face, one at the flexor edge and two at the extensor edge. The
fourth segment has five fine hairs on its extensor surface, one
in the posterior one-third, one about the middle, and the other
three scattered about the distal extremity. The flexor surface
has only one pore and rudimentary hair in its distal third.
Concerning the function of the long flexor bristle of the second
segment, Thor points out that when the palp is flexed, the
bristle can enter the mouth and by a slight lateral movement
can also enter the glandula globulosa. Thor's conjecture of the
function may be expressed thus — the bristle enters the pore of
the glandula globulosa, and by means of the pectination some
of the secretion adheres to it. The secretion may then be
conveyed to the claw of the mandible, and thus be used to
paralyse the victim whose juices are to be extracted, or it may
be conveyed by the bristle direct to the wound which the claw
has made.
THE GENUS LEBSRTIA. 489
The epimera form a shield which may cover from one-half to
two-thirds of the ventral surface, and in young specimens may
even go as far as four-fifths, while in the case of gravid females
the proportions may be entirely reversed. A change of colour
also manifests itself, the prevailing tint being pale blue or violet.
The inner sutures between the first and second pairs of epimera
do not extend up as far as the exterior interval between the
second and third pairs, and in this respect it is much shorter
than Thor's type Jimbriata. The inner end of the second pair is
scarcely any broader than Jimbriata. The lateral expansions of
the third pair are large, while the inner ends of the fourth pair
are somewhat, though not much, broader than the outer ends.
The posterior edges of the epimera are not so thick as in some
species. The length of the legs appears to be approximately, first
pair, 0"80 mm. ; second pair, 0'90 mm. to 1'10 mm. ; third pair,
1*25 mm. ; and fourth pair, 1*50 mm. to 1*60 mm. The various
segments are comparatively long, markedly so in the three last
segments of the two last pairs of legs, so that the considerable
length of the legs is accounted for. The terminal segments are
not so robust.
Thor has naturally compared the armature of the legs of this
species with that of his type Jimbriata, which he described in
detail. Although they have much in common, certain differences,
especially in the fourth pair of legs, are to be found. The out-
standing features of tau-insignita are as follows : the fourth
segment of the first and second pairs of legs has two or three
fine long bristles on the extensor surface. The third pair of legs
has three or four long pectinate bristles on the outer side
of the third segment ; the fourth segment has five bristles
similar to those of the first and second pairs of legs, and is
without swimming hairs. The fifth segment has three or four
shorter bristles standing close together, and has two swimming
hairs only. The greatest divergence is exhibited in the fourth
pair of legs. The second segment has two or three short bristles
distal on the extensor surface. The third segment has six
pectinate spines ranged round the distal extremity. The fourth
segment has six spines in a row on the flexor surface and one on
the inner surface. All are rather flattened at the extremity.
Six are pectinate, and swimming hairs are also wanting here.
The fifth segment has six short pectinate spines almost in a row
Journ. Q. M. C, Series II. — No. 76. 34
490 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
on the flexor surface, and two swimming hairs only. The small
spines of the sixth segment are generally six in number.
The genital area lies about one-fifth of its length out of the
recess or bay formed by the inner ends of the epimera. The
genital area is about 0*24 mm. in length, and at its broadest
about 0*1 7 mm. The anterior and posterior sclerites for muscle
attachment are not very robust. The valves are about 0*22 mm.
in length, and have five pairs of coarse pores along their outer
margins, and numerous hair pores along their inner edges. The
hairs are long, reaching almost to the anus. The two anterior
pairs of acetabula are very large, the posterior pair almost
rectangular. The gland pores occupy the normal position. The
anus lies about midway between the genital area and the posterior
body margin. Sexual dimorphism appears to be limited, so far
as external appearance is concerned, to the posterior region
of the genital area being rather wider in the male than in
the female, and to the hair pores along the edge of the genital
valves being more numerous, viz. twenty-four to twenty-eight for
the male, and twelve to twenty for the female.
Nymph.
Along with the imaginal forms, Thor obtained two nymphs,
which bear so close a resemblance to the imago of this species,
that he was constrained to accept them as nymphs of tau-
insignita. The body in comparison is rather more extended,
and is 0*68 mm. in length and 0'43 mm. in breadth. The skin
is striate and minutely porose. The structure of the palpi is
very much as in the imago, but the equipment of hairs is very
much simpler. The hairs are confined to the extensor surface.
The first segment is devoid of any hairs. The second has one
small one midway, and two very long distal ones close together.
The third segment has one long distal bristle and one a little
way behind it. The fourth segment has two or three very fine
hairs, of which one is well back, about or a little behind the
middle. The flexor surface resembles that of the imago. The
epimera differ from the adult form in that the fourth pair has
the appearance of not being properly developed. The posterior
angle has a little papilla-like projection. The legs are about
0*38 mm. long in the first pair to 0*75 mm. long in the fourth
THE GENUS LEBERTIA. 491
pair, and have only from one-third to one-half the nnmher of
hairs and spines present in the adult. Only one or two swimming-
hairs are to be seen. The provisional genital area has no vulva,
but two pairs of stipitate acetabula, surrounded by two semi-
circular chitinous structures, which almost meet together to form
a circle.
Lebertia Soari Sig Thor.
1905. Sig Thor, Zool. Anz., xxix. 55.
This species must be rejected, as it is founded on a diagram-
matic representation of what was at the time considered to be
the only species of the genus (vide Science Gossip, vi. 45, and
relative figures).
Lebertia fimbriata Si^ Thor.
(Sub-gen. Lebertia.)
1839. Lebertia Jimbriata Sig Thor — En ny hydrachnide-slegt og
andre nye Arter — 0. iVorli, Kristiania, p. 5. PI. xviii. fig.
172-175.
1905. Sig Thor, Zool. Anz., xxix. 41-52, figs. 5-17.
This hydracarid is of a dirty yellow colour, which is somewhat
masked by the large brown patches and the broad pale-yellow
strip on the back. It appears that the colour is apt to vary a
little. The legs are more transparent and of a paler colour than
the body. The epimera are about the same colour as the body,
but more iridescent. The body is soft skinned, without any
ridges or papillae, and has scattered over it many fine pores which
are covered externally by a fine membrane. The gland pores,
each accompanied by its fine guard hair, lie in four longitudinal
rows and are conspicuous by reason of the strong ring which sur-
rounds each of them. The length of the imago varies from abou
0*7 mm. to 0'9 mm., and if the anterior tips of the epimera are
included may even reach 1 mm. Viewed dorso-ventrally the
outline is a rather elongate ellipse, which is indented anteriorly
between the antenniform bristles. The dorsal surface is arched
very much more than the ventral. The tips of the first two pairs
of epimera, each with a long, fine, weakly pectinate hair, are very
noticeable beyond the anterior end of the body.
492 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDKACARINA :
The capitulum is rather elliptical in shape. Only the anterior
half is visible, the posterior half being concealed behind the
epimera. The two anterior processes are long, tapering to a
sharp point. In situ they are directed towards the posterior-
dorsal surface, but have very little tendency to spread apart
laterally. The posterior processes are very much shorter, but
similar in shape. Their direction, however, is straight into the
body, so that they partially enclose the pharynx. The pharynx
itself is fairly wide and thick and increases in size gradually
towards the posterior extremity. The mandibles are long and
slender, extending well beyond the posterior end of the pharynx,
and work in a furrow formed in the hinder wall of the capitulum.
The claws are very nearly straight and are weakly serrate.
Opposed to the claw is a laminar process which is nearly as long
as the claw.
The palpi vary in length from 0-35 mm. to 0*40 mm. The
third segment is shorter than the second, and the second shorter
than the fourth. They are thinner than the first pair of legs
and are laterally compressed. The second segment has a long
finely pectinate bristle on its flexor surface, slightly back from
the distal end. On the inner side of the segment almost distal
and close up to the extensor surface there are, close together, two
bristles which very nearly attain the length of the third segment.
The third segment has five weakly pectinate bristles on its inner
surface. Of these, three very long ones are at the distal
extremity, the fourth is short and situated close to the extensor
surface and slightly behind the middle, the fifth is longer than
the fourth and a little in advance of it and rather more to the
inside. The three distal ones are generally about the length of
the fourth segment ; one of these is close to the flexor surface and
two close to the extensor surface, one being slightly in advance of
the other.
The fourth segment has only one small pore and rudimentary
hair in the distal third of the flexor surface. The extensor surface
has five or six fine short hairs of which three are distal, one about
midway and the others between.
The posterior end of the first pair of epimera lies about midway
between the capitulum and the genital area. The posterior end
of the second pair is fairly broad. The suture between the
second and third pairs extends up about half-way to the gland
THE GENUS LEBERTIA. 493
plate on the outer border and then continues as a filiform exten-
sion coming well up towards the first pair. The third pair is
triangular with its suture extending inwards for about three-
fourths of the distance to the genital area. The fourth pair is
also three-sided, the outer side being not straight, but curving
well round to the inner posterior corner. The epimera are
perforated by numerous pores which are visible externally as
groups of fine pores.
The legs all have the first three segments short and the la.st
three long, and in addition it will be noted that the terminal
segments are rather thicker towards the distal extremity. The
first segment of all pairs of legs has three or four short spines on
the extensor surface ; in the case of the second and third pairs of
legs, one of these is longer, flattened and bipectinate ; in the
fourth pair of legs the segment is much larger than in the others.
The second and third segments apparently have some latitude in
their equipment of spines, but the distal ends have one or two of
these flattened bipectinate spines. The fourth segment of the
third pair of legs has one swimming hair, and the fifth segment
has three. The fourth segment of the fourth pair of legs re-
sembles that of the third pair, while the fifth segment has
two or three swimming hairs. The claws have a short thin
lamina.
The genital organ is pyriform in outline, the narrowed anterior
end being united to the epimera by a subcutaneous chitinous
strip. Posteriorly, the genital area extends for about one-third
of its length beyond the epimera and is bounded by an arc-shaped
chitinous ridge. The anterior sclerite is short and thick. The
two anterior pairs of acetabula are roughly rectangular, with
rounded corners, and are about twice as long as broad. The
posterior pair are more nearly round. The porose covering valves
have four or five large hair ports along their outer edge, and along
the inner edge there is a larger number of fine pores, which varies
with the sex, numbering in the female about twelve pairs and in
the male about twenty. The anal orifice lies about midway
between the genital area and posterior body margin.
L. jimbriata has been taken in Surrey and Suffolk. Halbert's
fimbriata of the Clare Island Survey has been redescribed as
L. celtica Sig Thor.
494 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA. :
Lebertia celtica Sig Thor.
(Sub-gen. Lebertia.)
1911. Lebertia fimbriata Halbert, Proc. Irish Ac, xxxi. (39i)
22, plate iii. fig. 31.
1911. L. celtica Sig Thor, Zool. Anz., xxxviii. 330.
Two specimens were taken at Clare Island and recorded as
fimbriata. From the short note and figure accompanying the
record Sig Thor came to the conclusion that these were sufficiently
distinctive in character to warrant a new species, L. celtica. At
first, Thor's new species did not seem to be well grounded, and
fimbriata var. celtica appeared to be better able to meet require-
ments. Careful examination of the types, however, leads to the
rejection of a mere variety in favour of celtica n.sp. In support
of this may be cited the elongate body form and relatively
contracted epimera, and the skin externally smooth but with
traces of ridges, either suppressed or of a rudimentary type.
The body is about 0*9 mm. long and 0*6 mm. broad. The
noticeable feature is the evenness of the sides, so that the body
is of about the same width throughout. The posterior end is
rounded, while the anterior end has a triple indentation, viz. one
at each of the corners and one between the antenniform bristles.
The colour is a golden brown, with dark patches on the dorsum.
Legs and palpi are greyish. Gland pores are arranged in four
rows on the dorsum ; each pore has a diminutive guard hair, and
is protected by a strong ring. The capitulum measures about
0*22 mm. in length, and the mandibles about 0*25 mm.
At present details as to the capitulum are not available, but
these will no doubt become so after further dissections of the
type have been made. The palpi are thinner than the first pair
of legs, and measure about 0*27 mm. in length. The armature
of bristles is as follows : on the extensor surface of the first
segment one bristle, and on that of the second segment three
short and two long ones at the distal end. The usual long
bristle is to be found on the flexor surface. The third segment
has the distal extremity rather stouter than is to be found in
fimbriata. The five bristles on the inner side occupy practically
typical positions, but the posterior one of the five appears to be
much longer than the corresponding one of fimbriata. The flexor
surface of the fourth segment is almost straight, and has only
THE GENUS LEBERTIA. 495
one pore in the distal third accompanied by a diminutive hair.
The extensor surface bulges out somewhat, and gives the im-
pression of a flattened arch. It has only one short hair midway
and two similar distal ones, one on each side. The fifth segment,
which is conical, ends in three claws, of which the back one is
smaller than the other two. The pores on the segments are not
large, but they are fairly evenly distributed right up to the distal
end of the fourth segment.
The epimera are rather long in comparison to the breadth,
bat this may be due to the fact that the sides are rather drawn
in towards the body, so that the whole epimeral area has a
slightly arched appearance. Anteriorly the epimera extend well
beyond the body margin. The first pair of epimera extends
posteriorly to half-way between the capitulum and the genital
area. The posterior ends of the second pair are broadened out,
and the suture which separates them from the other pairs
extends well up and tends to draw in towards the first pair.
The suture between the third and fourth pairs goes well on
towards that of the second pair, so that the third has an almost
triangular appearance. The fourth pair also may be described
as three-sided, as the outer side sweeps round from the third
pair to the genital area. The posterior corner in one of the
specimens is rounded, in the other it is truncated.
The first pair of legs measures 0 60 mm., the second pair
0*67 mm., the third pair 0*74 mm., and the fourth pair 0*87 mm.
At the base of each of the well-developed claws of the first
two pairs of legs there is a small claw-like process. The sixth
segment of the first pair of legs increases in thickness towards
the distal end, and is coarsely porose. The inner surface is
without hairs or spines. The fifth segment is similar in size
and shape to the foregoing, and has only one flattened spine
and two or three short hairs at the distal end. The fourth
segment, though somewhat similar, is rather stouter. The
third segment is shorter and stouter, with one flattened weakly
pectinate spine and three or four short ones distal. The sixth
segment of the second pair of legs is similar to that of the
first pair — it is, however, a little longer and more slender. The
fifth segment is a little longer than the sixth, and has three
or four short spines and one or two short fine hairs at the
distal end. The fourth is proportionately longer and stronger
496 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
than the foregoing, and has six or seven strong spines round
the distal end and three or four round the middle. The third
segment is shorter and stouter, and has five or six spines round
the distal end and three or four round the middle. One of the
distal spines is more like a bristle.
The third pair of legs has one short fine hair on the distal half
of extensor surface of sixth segment. The fifth segment has one
moderately long fine distal hair and one or two short spines
about midway. The fourth segment has six or seven spines of
varying length round the distal end and four or five round the
middle. The third segment has four or five spines of varying
length and stoutness round the distal extremity, and a similar
number of shorter ones round the middle.
The sixth segment of the fourth pair of legs has two short
spines on the distal half. The fifth segment has two moderately
long fine swimming hairs and five or six short thin spines at the
distal end. There are six or seven short thin ones on the inner
edge and two short ones on the outer edge. The fourth segment
has five or six short spines along the inner edge and four on the
outer side.
The valves of the genital area lie close up to the posterior
ends of the second pair of epimera and extend posteriorly beyond
the epimera for about one-fourth of their length. Along the
inner edge of the valves there are about seven pairs of hair
pores. The two anterior pairs of acetabula are long and narrow.
The posterior pair are shorter and broader.
Lebertia insignis Neuman.
(Sub-gen. Pilolebertia.)
1880. Lebertia insignis Neuman. Kgl. Sv. Vet. Akad. HandL,
xvii. (3), 68-70, pi. viii. fig. 4.
1906. Sig Thor, Zool. Anz., xxix. 784-790, figs. 50-53.
Viewed from the critical standpoint from which the genus is
now considered, it is not to be wondered that Neuman's description,
written about thirty-five years ago, should treat rather differently
some details which recent writers have considered of some
moment. Any doubts, however, which might have arisen as to
Neuman's species can now have little force, as Sig Thor has
THE GENUS LEBERTIA. 497
examined Neuman's type specimen and supplied what was
deficient in the original description.
The species is distinguishable first of all by its small size,
which is variable and may range from about 0*8 mm. in length
to slightly over twice that size. The greatest breadth is a little
under that figure. As a rule the body is somewhat dorso-
ventrally compressed and varies from a broad oval to nearly
round. The anterior is without any weak marginal indent —
rather bluntly rounded. The apical extremities of the first and
second pair of epimera extend only slightly beyond the body
margin.
The colour may be a reddish brown or a }'ello\vish red with
large brown spots, with the excretory organ showing through as
a broad T- or Y-shaped strip on the dorsum. The epimera have
a tinge of blue or green. The palpi and legs may also have these
colours or even a bright red, but in these appendages the
colours are fairly transparent.
Beyond being thinner, the skin is similar to that of porosa.
The capitulum also resembles that of porosa, but it is
decidedly smaller. The tapered anterior processes are of
moderate length and do not spread out very much laterally.
While the mandible closely resembles that of the allied species,
it is also more symmetrical in its build. The posterior portion
is weakly sinuate with the extremity sharply turned up. The
pharynx, like the mandible, is also more symmetrical.
The palpi appear to have some latitude in regard to their
length, as the extremes of 0'30 mm. and 0*48 mm. have been
recorded. The Irish specimens are even larger, viz. 0'52 mm.
The second segment has five or six bristles on the extensor surface,
while the characteristic bristle on the flexor surface is short, and
though it is distinctly back from the distal extremity of the seg-
ment, it is not so much as is to be noted in, say porosa or obscura.
The third segment has five long finely pectinate bristles on the
inner side. Three of these are close to the extensor edge. The
proximal and distal ones each stand slightly back from their
respective ends of the segment, while the middle one is more on
the edge than the other two. The remaining two stand close
together distally almost at the flexor edge. This feature rather
marks out insignis from other species of the sub-genus. While
the middle one of the three distal bristles is typically towards the
498 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
flexor surface, this appears to be more decidedly shown in
insignis (Thor's two figures do not agree as to this. Of. Zool.
Anz., xxviii. 821, fig. 1, and xxix. 788, fig. 53). All the short
fine hairs on the fourth segment are distal.
The epimera are relatively larger than in sub-genus Lebertia.
As a rule the breadth is greater than the length. The lateral
extensions of the epimera embrace that portion of the sides
abutting on the epimera. It must be remarked here, however,
that these extensions can only be observed in certain positions
if the creature is not dissected. In preparations where the
epimera are removed, or the body is flattened out, the extensions
can be readily seen. The first pair of epimera is of normal
form. The second pair is narrow and of almost uniform
width throughout. If the suture between the third and fourth
pairs were continued for the full length, it would just about meet
the inner end of the suture between the second and third pairs,
showing the third pair to be almost triangular in form. The
fourth pair is broader at the inner end than at the outer.
The outer edge is lightly rounded.
The legs measure up to 1*00 mm. in the first pair, 1*25 in the
second pair, 1*70 mm. in the third pair and 205 mm. in the
fourth pair. The fourth, fifth and sixth segments of each pair
of legs are much longer than the other segments. The sixth
segment of the second, third and fourth pair of legs is more
or less thicker at the distal extremity than at the proximal. The
first segment of the fourth pair of legs, which is much larger
than the corresponding segment of the other pairs, has on its
extensor surface one or two small proximal bristles and distally
two much longer ones. The flexor surface has one distal bristle
with two accompanying hairs. The flexor surface of the sixth
segment has generally only three spines. The swimming hairs
are short, relatively few and variable in number. The fifth
segment of the second pair of legs may have from five to seven.
With respect to the third and fourth pairs of legs, the fourth
.segment may have up to eight, and the fifth segment up to twelve.
The genital area extends a little beyond the epimera.
Posteriorly it is bounded by a thick chitinous curving ridge and
anteriorly by a stellate sclerite which forms a bridge between it
and the epimera. The valves and acetabula are of normal form.
Along the inner edges of the valves there are a number of hair
THE GENUS LEBERTIA. 499
pores, ranging in the female up to sixteen, and in the male up to
twenty-five.
Nymph.
The nymphs are about 0*60 mm. in length and 050 mm. in
breadth. The fifth segment of the second pair of legs has two
swimming hairs. The fourth segment of the third and fourth
pair of legs has only two swimming hairs, and the fifth segment
only four swimming hairs. The flexor surface of the sixth
segment of the fourth pair of legs has only one small spine.
This species has been found in Great Britain and Ireland, as
well as Norway, Sweden, Finland, Germany, Switzerland and
Italy.
Lebertia vigintimacidata Sig Thor is now considered by its
author to be merely a variety of the above and other species
(vide. Zool. Anz., xxix. 786).
Lebertia porosa Sig Thor.
(Sub-gen. Pilolebertia.)
1897. L. tau-insignita et insignis Thor. Ark. Math. Naturv., xix.
(6) 31 ; xx. (3) 18.
1900. L. porosa Thor. Nyt. Mag. Naturv., xxxviii. 273.
1905. Sig Thor, Zool. Anz., xxix. 761.
Lebertia porosa is one of the species attaining a large
size. Considerable variation appears to exist with regard to
length, as specimens have been recorded from 0'9 mm. up to
2-l mm., with a corresponding breadth varying from 0 85 mm.
to 1'9 mm. The most common length appears to be about 1 mm.
or a little over, and the breadth about 01 mm. less than the
length. The body is oval to almost round, frequently slightly
dorso-ventrally compressed. The anterior end is rounded, with
the apices of the first and second pairs of epimera extending
a little beyond it. The colour is a dark reddish brown or a
yellowish red with brown spots, with the excretory organ showing
through as a bright-yellow T-shaped dorsal figure. The epimera
may show a faint bluish or greenish tinge, while the palpi and
legs are more transparent, and evidently more variable as to
colour, as red, green, blue, or bluish green are found. Thor has
pointed out that the action of preservative solutions on the
500 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
colours is erratic. Thus, for example, of two specimens subjected
to identical treatment, one may bleach out, while the other
retains its colours, or all or part of the dark spots may remain
while the rest of the colour may fade. Thor conjectures that
the condition of the dermal glands may have some bearing on
this question. The skin is rather thick, smooth and strewn over
with fine pores.
The anterior maxillary processes are long and broad, tapering
to a point, and extend in an upward, lateral direction towards
the posterior, but not so far as to meet the pharynx or the
posterior processes. The latter have their extremities curved
upwards so as, in a manner, to enclose the pharynx.
The palpi are laterally compressed, and are thinner than the
first pair of legs. The length varies from 04 mm. to 0*6 mm.
The third segment is always shorter than the second and fourth
segments. It should be noted that compared with the second
and third segments, the pores of the fourth segment are much
finer. These gradually disappear towards the distal extremity,
so that that region has a very much smoother appearance. The
first segment has only one short slightly curved bristle on its
extensor surface, where the second segment has six or seven. Of
these the two distal ones are long and thin, and stand back from
the distal extremity of the segment. The characteristic fine
pectinate bristle on the flexor surface is weak and not particularly
long, being generally about half the length of the segment or a
little over that. The third segment has five finely pectinate
bristles ; one of these is proximal and close to the second segment,
while another is about the middle, rather more on the extensor
surface than on the inner. These two are generally shorter than
the other three, which are distal, and about the length of the
fourth segment. The middle one of that three is about equi-
distant from the one on each side as in obscura. The fourth
segment has two distinct pores on its flexor surface, each with a
rather rudimentary hair. One of these pores is in the proximal
third, the other may be so far forward as to be in the distal
third. The five fine hairs on the extensor surface are all distal.
The fifth segment is small, almost conical, ending in two small
claws lying close together, with a small one behind them.
The epimera agree very closely with those of insignis, with the
exception that the inner ends of the second pair are much
THE GENUS LEBEliTIA. 501
broader in porosa than in ins ignis. The inner corners of the
third and fourth pairs of epimera are more rounded, not so
acute as in insignis. All the sutures and margins are thick,
the inner ones particularly so.
Some variation appears to manifest itself with regard to the
length of the legs, but in general it may be said that the two
anterior pairs of legs are short, and that the two posterior pairs
attain something like the length of the body or a little over.
The sixth segments are either weakly thickened or not at all.
The sixth segment of the first pair of legs is not thickened,
but reduced in length. The thickening of the corresponding
segment of the second pair of legs is scarcely appreciable, more
so, however, in that of the third and fourth pairs of legs. The
first three segments of each pair of legs are the shortest, the
other three the longest. In comparing the first segment of each
pair of legs, it will be noticed that that of the fourth pair of legs
is by far the longest. Swimming hairs are entirely wanting in
the first pair of legs. The second pair has a small group
clustered at the distal end of the fifth segment ; these are not so
long as the succeeding segment. The third pair has five to ten
long swimming hairs at the distal end of the fourth segment, and
eight to fifteen at the end of the fifth segment. The fourth pair
of legs has five to nine long hairs at the distal end of the fourth
segment, and anything from eight to seventeen at the end of the
fifth segment. The claws appear to be of normal form, a large
thin claw with a thin broad laminate base, and in the narrow
interval between a small accessory claw.
The genital area is fairly typical in form, and extends but
little beyond the epimera. The male is distinguishable from the
female by the greater breadth posteriorly in the valves and by
the number of gland hairs along the inner margins, viz. twenty
to thirty-three where the female has only from fourteen to
twenty. The large pores along the outer margin are few in
number, not more than five pairs at the most. Of the sclerites
which serve for muscle attachment, the anterior one is triangular
in shape, with its apex continued into a narrow bridge to bind
it to the epimera. The posterior one is broad and porose, and
is more like a semicircle in outline. The two anterior pairs of
acetabula are long and narrow, rather rectangular, with rounded
corners. The posterior pair is much shorter and broader.
502 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
Nymph.
The nymph is about 0*70 mm. in length and about 0*65 mm.
in breadth. The palpi are pretty much like those of the imago
so far as the structure is concerned, but in re&pect to the number
and arrangement of the bristles there is a marked difference.
The first segment has none at all ; the second has two on the
extensor surface and one distal. The third segment has only
two long bristles, both distal, one on the extensor surface and
one midway on the inner surface. The distal extensor surface of
the fourth segment has only three short ones, in other respects
it resembles the imago. The provisional genital area does not
extend beyond the epimera. The surrounding ring, which is in
communication with the epimera anteriorly by a small sclerite,
has about six fine pores. The four acetabula are stijDitate.
Var. britannica Sig Thor covers some British specimens which
have the posterior pair of acetabula about the length of the
second pair instead of much shorter as is usually the case (Zool.
Anz., xxix. 776).
Var. vigintimaculata Sig Thor has presumably the same
characteristics as the variety of the same name under L. insignis
(ib. 786).
Var. dorsalis Sig Thor has the middle distal bristle of the
inner surface of third segment placed more towards the extensor
surface (ib. 779).
Var. italica Sig Thor. Specimens from Lake Maggiore have
the legs, epimera and palpi of a decided greenish -blue colour
(ib. 779).
These latter forms are evidently local, but it is open to ques-
tion whether they have sufficient claim to be ranked as varieties.
Lebertia porosa has been recorded for Britain and appears to
have a fairly wide distribution, as even Siberia has added its
quota to the recorded distribution.
Larva.
The outline is approximately oval, and measures about
0*3 mm. in length and 0'2 mm. in breadth. The body is dorso-
ventrally compressed, and this applies particularly to the posterior
region. The dorsum and venter are both protected, the former
by a chitinous plate, which extends nearly to the edge of the
THE GENUS LEBERTIA. 503
body, and the latter by the epimeral plate, which is similar in
size to the dorsal plate. The skin of the lateral surface between
the edges of the plates is soft and marked by tine lines running
the length of the body. Along this area dorsally there are nine
pairs of long stiff bristles in two rows, an inner of four pairs and
an outer or more lateral one of five pairs. The dorsal plate has
three pairs — two pairs lying close -3 front of the eyes and a
small pair representing the antenniform bristles. The ventral
surface also has a few hairs — two pairs on or near the edge
of the epimeral plate posteriorly being pectinate. Quite a
number of these hairs may extend beyond the margin of the
body.
The capitulum is about 0-0S mm. long. It extends well beyond
the bay formed by the first pair of epimera, and curves well
towards the ventral surface. About midway up each side the
palpi are articulated. The third and fourth segments are pro-
minent by reason of their stoutness. The third segment has one
strong bristle on its outer side, while the fourth has a moderately
long curved claw. The fifth segment is of a rudimentary type :
it lies somewhat recessed into the fourth segment, and has two
long and three short hairs springing from it.
The larva possesses only three pairs of legs, which are grouped
well, towards the anterior end of the body. The first pair may
measure up to 0*20 mm., the second pair 027 mm., and the third
pair 0*30 mm. Swimming hairs are entirely wanting, but loco-
motion is aided by a varying number of moderately long, simple
or weakly pectinate straight bristles, which are to be found in
greatest abundance on the third pair of legs. Each leg ends
in three fine, long, curving claws, of which the middle one is the
smallest.
Corresponding to the number of pairs of legs, there are only
three pairs of epimera. The suture dividing those of one side
from the other is well marked, as well as that dividing the first
pair from the second. Only a very short rudimentary lateral
suture separates the second pair of epimera from the third. The
posterior portion of the third pair is cut away obliquely on the
median line ; within this recess there is a small weakly chitinised
post-epimeral plate, which Piersig called the anal plate, but
which Thor prefers to consider as the rudiment of the provisional
genital area found in the nymph.
504 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA I
Lebertia obscura Sig Thor.
(Sub-gen. Pilolebertia.)
1900. Lebertia porosa var. obscura Sig Thor. Nyt. Mag. Naturv.,
xxxviii. 273, pi. x. figs. 3 and 4.
1902. L. obscura Sig. Thor in Arb. Inst. Wien, xiv. (2) 11, pi. i.
fig. 9-
1906. Sig Thor, Zool. Anz., xxix. 780, figs. 47-48-54.
Lebertia obscura was, by reason of its closeness to L. porosa,
first considered by Thor to be only a variety of that species, but
his exhaustive investigations on the genus led him to elevate
obscura to the rank of a distinct species. When obscura and
porosa are contrasted, it will be noted that the former is some-
what the larger of the two, ranging from 1*5 mm. to 2 "5 mm. in
length, and in general it appears to be of a more robust build and
somewhat darker colour.
The palpi measure up to about 0'65 mm. in length, and viewed
ventrally are scarcely so stout as the first pair of legs. Compared
with porosa the long bristle on the flexor surface of the second
segment is relatively shorter and situated rather more distally,
the third segment is shorter in proportion, while the fourth is
broader and straighter, with the two pores on the flexor surface
frequently situated close together. As a general rule the fifth
segment is shorter and more blunted.
The legs are thick and strong. The first pair measures about
0*96 mm., the second pair about 1*36 mm., the third pair about
1*70 mm., and the fourth pair about 1*92 mm. in length. The
fourth pair is to be noted as possessing in the fifth and sixth
segments a larger number of spines and swimming hairs than in
the closely allied species, and also what Thor deems a characteristic,
the possession of 5 or 6 spines, 3 or 4 of these being distal, on the
extensor surface of the first segment, instead of the 3 (more rarely
4), 2 of them being distal, generally associated with other Pilo-
lebertia species.
L, obscura does not appear to be a widely distributed species,
as so far it has only been reported from Norway, Scotland and
England.
THE GENUS LEBERTIA. 505
Lebertia Halberti Koen.
(Sub-gen. Mixolebertia.)
1902. Lebertia Halberti Koenike, Zool. Anz., xxv. 610.
This species was taken by Halbert at Dartrey in Ireland
in 1899, and so far only the male appears to be known. In
outline the body is oval, being about 1*36 mm. in length and
about 1*20 mm. at its broadest part. The colour of the body is
a dark green — described by Koenike as a greenish grey — the
dorsal surface being adorned on each side of the median line by a
row of roundish dark spots. As is not uncommon, the colour of
the limbs and palpi is much weaker than that of the body. The
skin is without the strong ridges noticeable in other species, but,
notwithstanding, it is adorned by fine lines crossing one another
as to form an elongated mesh work.
The palpi are 0'43 mm. in length, the segments being respec-
tively 0-04, 0-10, 0-10, 0-16 and 0'03 mm. in length, and in their
bristle armature they closely follow the type. The first segment
has one short distal, slightly curved spine on the extensor surface.
The second segment has two similar but rather larger spines
on the middle of the extensor surface, and on the distal inner
surface adjacent to the extensor surface two moderately long
bristles. The distal flexor surface is armed with the usual long
bristle. A noticeable feature is the presence of six bristles, extend-
ing nearly to the distal end of the fourth segment, on the inner
surface of the third segment. Three of these are distal, one being
adjacent to the flexor surface and the other two close up to the
extensor surface, one being practically on the extensor surface. Of
the other three, one is proximal, while the remaining pair is
situated about midway and occupies about the same position
as the pair anterior to it, if anything rather more towards the
extensor surface. The fourth segment has four fine hairs grouped
at the distal extensor extremity. The posterior of the two pores
on the flexor surface is accompanied by the typical moderately
long hair.
The lateral processes at the anterior end of the capitulum
have very little tendency to spread out laterally — they extend
inwards until their extremities are about in line with the base
of the posterior pair. The claws of the mandibles have a row
of fine teeth on their concave side.
Joirax. Q. M. C, Series II.— No. 76. 35
506 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
The legs are rather more slender than in L. insignis, and this
may be attributed to the fact that the fourth, fifth and sixth
segments of the second, third and fourth pairs of legs are
decidedly longer. The fifth segment of the second pair of legs
has swimming hairs, the length of which about equals that of
the segment itself.
The inner posterior ends of the second pair of epimera just in
front of the genital valves are decidedly thickened, and are about
twice as broad as in L. insignis. The fourth pair of epimera is
nearly of equal width throughout, any tendency to increase
manifesting itself towards the inner end, where the posterior
corner is broadly rounded off.
The genital area extends for about one-third of its length
outside the bay formed by the fourth pair of epimera. The
thick chitinous ridge which forms the posterior boundary of the
area lies close in and extends a little way up the sides. The
third pair of acetabula is very little shorter than the other two
pairs. A few hairs may be noted along the posterior margins
of the valves.
Lebertia glabra Sig Thor.
(Sub-gen. Pseudolebertia.)
1897. Lebertia glabra Sig Thor, Arch. Math. Naturmd., xx. (3),
19, pi. iii. fig. 23.
1907. Sig Thor, Zool. Am., xxxi. 105-115, figs. 73-81.
Lebertia glabra appears at present to be limited to Norway
and Scotland. It belongs to the smaller species, and appears to
vary from about 0'6 mm. to 1*1 mm. in length, and about
0'5 mm. to 1*0 mm. in breadth. In outline, the body presents
a somewhat rounded appearance, and, viewed from the side, the
venter is seen to be much less arched than the dorsum. The
dorsal surface is of a brownish -yellow colour with dark-brown
patches, and is rendered conspicuous by the pale-yellow T-shaped
figure of the excretory organ showing through. The ventral
surface and the legs have a tinge of green in their colouring.
The skin is covered with short chitinous ridges, some of which
may even be forked. On the dorsal surface these are quite short
and lie more or less parallel to the long axis of the body. On
the ventral surface they are longer and run transversely. In
THE GENUS LEBERTIA. 507
proximity to the epiinera, genital and anal areas the ridges to
some extent follow the outline of these more highly chitinised
structures. The skin would appear to be thin, as Thor has
been unable, except in isolated cases, to detect the groups of fine
pores which are prominent in other species, though the epimera,
genital valves, legs and palpi exhibit the coarsely porose appear-
ance to be found throughout the genus.
The capitulum is of the form normal to the genus, and is about
0*22 mm. in length, with a breadth of nearly 0*12 mm. It does
not fully take up the area bounded by the inner margins of the
first pair of epimera. While the anterior processes of other
species have an upward and outward tendency, i.e. towards the
interior of the body, in this species they are more slender and
come closer in to the capitulum, lying more in a horizontal
direction and less towards the interior of the body. The posterior
processes are fairly slender. The mandibles, like the anterior
processes, are more drawn in towards the capitulum than is
usually the case. They are fairly long, and extend beyond the
pharynx and the extremities of the anterior processes. An
average length for the palpi would appear to be slightly over
one-third of a millimetre. The fourth segment is longer and
thinner than the two preceding ones, while the fifth is relatively
long and thin and tapered. The extensor surface of the first
segment has one long fine bristle. The corresponding region of
the second segment has four bristles, of which the two longest
are almost distal, while on the flexor surface, set well back from
the distal extremity, there is a strong, curving bristle, which is
moderately long and finely pectinate. The inner surface of the
third segment has five bristles ; three of these are distal, finely
pectinate, and about as long as the fourth segment. The middle
one of the three lies rather more towards the bristle at the
extensor edge, which happens to be a little less distal than
its companions. The fourth bristle lies about the middle at
the extensor edge of the segment, while the fifth lies slightly
behind it and rather more inwards. The distal extensor surface
of the fourth segment has six hairs of varying length ; five
of these are more or less grouped about the distal extremity,
but the sixth lies farther back. The flexor surface has the
usual two fine pores with accompanying diminutive hairs; one of
these pores lies about the middle, the other one is nearly proximal.
508 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
The epimera are about as broad as long, a trifle over 0*7 mm.
The lateral expansions are well developed, and the sutures between
the epimera are very thick. This applies also to the posterior
margins, which are rather broader than usual. The inner edge
is nearly straight, having a clean-cut appearance. The width
of the fourth pair is nearly equal throughout, the outer edge
having -<> ''times a slight concavity near the gland pore, at
other times it is slightly rounded. The point where the fourth
pair of legs articulates with the epimera lies well in from the edge
of the latter, so that about two-thirds of the first segment of the
leg lies over the lateral expansion. The recess for the capitulum
is about the same length as that for the genital area, but the
latter widens out posteriorly.
The legs are of normal structure, and in the case of the third
and fourth pairs may attain to, or even slightly exceed, the
length of the body. The terminal segments of the second, third
and fourth pairs are distinctly enlarged towards their extremities,
but in the case of the corresponding segments of the first pair,
if the enlargement exists, it is only weakly developed. None of
the legs have swimming hairs.
The genital area is about 0'23 mm. in length and about
0'15 mm. in breadth, and extends for about a fourth of its
length beyond the epimera. The lunate plates for muscle
attachment which lie at each end of the genital area are fairly
well developed. Along the inner edge of each of the valves,
there are a number of hair pores. The acetabula are of normal
form, and decrease slightly in size from the anterior pair to
the posterior pair. The anus is only weakly chitinised, and is
without the strong ring observable in some other species.
Externally, the sexes appear to be hardly distinguishable from
one another.
Nymph.
Thor's observations on the nymph may be summarised as
follows. The length ranges from 0'43 mm. to 0-55 mm., and the
breadth from 035 mm. to 0'48 mm., so that the outline may
vary from oval to nearly round. The colour is about that of the
imago, though sometimes it may be brighter and more trans-
parent. The skin is thin and ridged as in the imago. In the
nymph, however, the ridges are smaller and not so abundant as
THE GENUS LEBERTIA. 509
in the imago, the intervals being twice as great as in the latter.
Any fine pores which may be present are extremely difficult to
detect. The capitulum and the epimera resemble those of the
adult form.
The palpi are about 0'22 mm. in length. The first segment is
devoid of bristles. The second segment has one or two bristles
distal and one about the middle of the extensor surface. The
third segment has two rather long distal bristles, one at the
extensor surface and the other about midway on the inner
surface. The fourth segment has the usual two pores on the
flexor surface.
The legs are about 0*40 mm. long for the first pair; 0*45 mm.
for the second pair ; 0'52 mm. for the third pair, and 068 mm.
for the fourth pair. The terminal segments of the second,
third and fourth pairs are like those of the adult. Swimming
hairs are also wanting.
The provisional genital area has four acetabula surrounded
by a chitinous ring, which is open towards the posterior and
anteriorly is attached to the ligulate muscle attachment plate.
The larval stages are at present unknown.
Lebertia stigmatifera Sig Thor.
(Sub-gen. Heocalebertia.)
1900. Lebertia stigmatifera Sig Thor Nyt. Mag. for Naturvid.,
xxxviii. 275-276, pi. xi. figs. 7-9.
1907. Zool. Anz., xxxii. 150-157, figs. 87-90.
Lebertia stigmatifera was taken by Mr. Deeley in Worcester-
shire. It is here recorded as an addition to the fauna of the
Britannic area, and is another link in the chain connecting the
Scandinavian and British faunas. It belongs to the smaller
species, a common size being about 0'7 mm., though extremes
of 0'58 mm. to 1*05 mm. have been recorded.
The body is very nearly circular in outline, with the anterior
margin rather flattened. The ground colour of the body is
yellow, with large brown patches and the usual T-shaped yellow
outline on the dorsum. The skin is comparatively thin, and is
adorned with chitinous ridges, for the most part lying parallel to
one another. The skin is very indistinctly porose ; in the case
of the more heavily chitinised parts, the common large pores are
510 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
to be found. The second and third segments of the palpi show
the usual groups of fine pores, but in the fourth segment these
gradually disappear towards its distal extremity.
The capitulum is of normal form, but rather small, as it does
not quite take up the bay formed by the first pair of epimera.
The posterior processes are short and thick. The mandibles
are slender in structure, and about a quarter of a millimetre
in length.
The palpi are about 0'4 mm. in length, and more slender than
the first pair of legs. The fourth segment is distinctly longer
than the third, and not quite so stout. The first segment has
only one fine bristle on its extensor surface. The second
segment is porose, and has four or five short bristles on its
extensor surface. The characteristic bristle on the flexor surface
is nearly straight and very slightly pectinate. It stands
distinctly back from the distal edge. The third segment is
also porose, and carries the characteristic of the sub-genus,
namely, six long bristles on the inner surface of the segment.
Of the three which are almost distal, two are close to the
extensor surface. The fourth is not quite proximal, and is close
to the extensor surface also. The remaining two are just a
little posterior to the middle line — one is at the extensor surface
and the other just inside of it. All the bristles are very long,
some going beyond the distal end of the fourth segment. The
fourth segment is weakly porose, and it should be noted that the
two fine pores on the flexor surface are very close to one another
and the accompanying hairs are very short. The rest of the fine
hairs are grouped distally. The fifth segment is very short
and tapered.
The epimera are of unusual size and possess an extension laterally
and posteriorly which forms quite a characteristic feature, and is
apparently most marked in the male. The fourth pair of epimera
are so large as to include within the posterior margin the gland
pore usually found outside. The articulation of the fourth pair
of legs also lies well back from the lateral margin. The lateral
expansion sometimes draws so far forward as to come close up to
the second epimera. Just behind the third pair of legs, the
expansion of the epimera encloses a large gland pore. The posterior
inner edge of the fourth pair is nearly straight, making the
corner almost right-angled. At each corner a short hair will be
THE GENUS LEBERTIA. 511
observed. The anterior ends of the first and second pairs of
epimera have each a moderately long hair. There are two or
three short hairs behind the first segment of the third and
fourth pairs of legs. The posterior extremities of the first pair
of epimera end in a point about midway between the capitulum
and the genital area. The second pair also ends in a point, but
this is just at the genital area, where it is fused with the
extremities of the third pair. The fourth pair is rather more
rectangular, as the inner end is not broader than the outer. The
epimera appear to be more fused together in the inner area.
The sutures are broad, but not well defined.
The legs, which are devoid of swimming hairs, do not appear to
possess any outstanding features of much moment. The distal
end of the sixth segment is little, if any, stouter than the proximal
end. The fourth pair of legs lies close up to the suture between
the third and fourth pairs of epimera. The first segment has
six spines on its extensor surface. The fifth segment has eight
to eleven spines and the sixth segment five or six spines on the
flexor surface. The claws are of normal form and size.
The genital area is small. In the female it extends very little
beyond the epimera, and in the male not at all. The strong
anterior sclerite is roughly triangular in shape. The posterior
one is slender and arc shaped. The acetabula do not call for
special comment. The posterior one is almost round and much
smaller than the two anterior elongated ones. The valves have
six to nine large pores along their outer edge, and along the inner
edge there are a number of fine hair pores, ranging in the case of
the female from twelve to fifteen and in the case of the male from
nineteen to twenty-four.
The anus is surrounded by a strong outer chitinous ring.
Nymph.
So far the nymph has not been found among collections outside
of Norway. The length appears to range from 0'50 to 0*63 mm.,
and the breadth 0*45 to 0*55 mm. The colour of the oval-shaped
body is about that of the imago, while the skin is covered with
fine chitinous parallel ridges.
The palpi are thick and about 0*22 mm. in length. The first
segment has no bristles. The second has three on its extensor
surface, of which one is distal. The third segment has three long
512 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA :
bristles on its inner side, one of these being nearly proximal and
the other two almost distal, one of them being on the extensor
surface and the other just inside of it. The fourth segment has
three fine hairs distal on the extensor surface, and two fine pores
close together on the flexor surface as in the imago.
The epimera are relatively short and broad. The area between
the fourth pair of epimera is relatively wider than in the imago,
but the fourth pair itself is much narrower, so that the
gland pores lie well outside. The inner ends of the second pair
are much broader, while the inner ends of the fourth pair are
cut away very obliquely. The provisional genital area lies about
half-way beyond the epimera. The outer ring is rather more
oval than round and has only four minute pores. The sclerite
between the genital area and epimera lies close up to the epimera.
The anal ring is broad but not strong.
The legs have no swimming hairs, though a single long hair at
the distal end of the fifth segment of the fourth pair of legs may be
observed. The first segment of the fourth pair of legs differs from
the corresponding segment in the nymphs of other sub-genera in
the possession of three bristles on the extensor surface.
Lebertia trisetica Sig Thor.
(Sub-gen. Hexalebertia.)
1907. Lebertia trisetica Sig Thor. Zool. Anz., xxxii. 157, fig. 91.
This form is allied to L. stigmatifera, but in comparison with
it trisetica will be found to possess a thicker skin, the ridges on
which are stronger and broader, with a greater tendency to
branching. The intervals between the ridges are broader and
minutely porose. So far as can be judged from preserved
material, the colour would appear to be a reddish brown with a
tinge of yellow.
In outline the body is oval or elliptical, with a length of about
0*9 mm. and a breadth of about 0*7 mm. Between the antenni-
form bristles the anterior margin is weakly concave.
The capitulum is about 0*21 mm. in length, with the lateral
processes of moderate length and pointing in an antero-lateral
direction.
The palpi are relatively slender, and are a little over 0*4 mm.
in length, the individual segments being about 0*035, 0*102,
THE GENUS LEBERTIA. 513
0-110, 0*143 and the terminal segment 0034 mm. It will be
observed that the third segment is a little longer than the
second. The second and third segments are minutely porose,
but the fourth is not. The distribution of bristles agrees fairly
well with that of the allied species, but it is to be noted that
those on the extensor surface of the first and second segments
are stronger, while the bristle on the flexor surface of the
second segment is very long and fine, and is curved upward.
The striking characteristic of this species is to be noted slightly
in advance of the middle of the flexor surface of the fourth
segment in the shape of three fine pores with minute setae,
whence the specific name of trisetica.
The epimera are strongly developed with thick sutures, and
the inner posterior corners of the fourth pair almost rectangular.
The genital area is about 0*22 mm. in length, with about one-
fourth projecting posteriorly beyond the epimera. The inner
edges of the valves have about twenty fine hairs distributed
along their length. The acetabula are long, particularly the
two anterior pairs.
The anus lies near the posterior body margin, and is sur-
rounded by a stout ring. The gland pores on each side stand out
conspicuously, as well as those at the posterior inner corner of
the fourth pair of epimera.
The species was described from material taken in Surrey
in 1896, and so far it has not been recorded from anywhere else.
DESCRIPTION OF PLATES.
Plate 33.
Fig. 1. L. porosa. Dorsal surface, x 22.
„ 2. L. porosa. Epimera of adult, x 66.
„ 3. L. porosa. Epimera of nymph, x 66.
„ 4. L. porosa. Larva, ventral surface, x 94.
Plate 34.
Fig. 1. L. tau-insignita. Ventral surface, x 26. (After Sig
Thor.)
2. L. tau-insignita. Genital area, x 80. (After Sig Thor.)
3. L. tau-insignita. Inner side of left palp, x 133. (After
Sig Thor.)
5>
514 W. WILLIAMSON AND C. D. SOAR ON BRITISH HYDRACARINA.
Fig. 4. L.fimbriata. Inner side of left palp, x 133. (After Sig
Thor.)
„ 5. L.fimbriata. Fourth leg, x 60.
„ 6. L. trisetica. Dorsal surface, x 39.
,, 7. L. trisetica. Fourth leg, x 00.
,, 8. L. trisetica. Inner side of left palp, x 147. (After Sig
Thor.)
„ 9. L. trisetica. Skin markings.
,, 10. L. stigmatifera. Inner side of left palp, x 147. (After
Sig Thor.)
„ 11. L. stigmatifera. Genital area, x$Q.
„ 12. L. glabra. Inner edge of right palp, x 147. (After Sig
Thor.)
,, 1 3. L. glabra. Fourth leg, x 60.
„ 14. L. porosa. Fourth leg, x 60.
,, 15. L. porosa. Inner edge of right palp, x 117. (After Sig
Thor.)
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 76, April 1915.
Jourx. Q.M.C.
Ser. 2. Vol. XIL. PL 33.
•
*=*=*,
i ft :;
C. D. Soar, del ad nat.
The Genus Lebertia.
Journ. Q.M.C.
Sri'. 2, Vol. XII., PL 34.
C. D. Soar, del.
T
The Genus Lebertia.
515
A "NEW" OBJECT GLASS BY ZEISS.
By J. W. Gordon.
{Read March 23rd, 1915.)
Figures 1 and 2.
In the November number of the Journal of the Club there
is a paper by Mr. Nelson upon a new object glass by Zeiss.
Of this object glass Mr. Nelson speaks in high praise, and no
doubt it merits the encomium which he bestows upon it. Besides
describing its performance, Mr. Nelson attributes entire novelty
to the plan upon which this objective is constructed. That plan
is the fitting of an oil -immersion front lens to a |-in. dry
objective so that an oil-immersion objective is produced having
a numerical aperture less than 1. Mr. Nelson certifies that, so
far as his knowledge goes, this type of objective is quite new.
From the merit of Messrs. Zeiss in recognising the advantage
to be secured by applying the oil -immersion front lens in this
way, I do not at all wish to detract ; but it is perhaps worth
while to point out that the idea is not quite so new as Mr. Nelson
supposes. So far back as July 1909, Messrs. It. &, J. Beck
produced and supplied to me a lens which was precisely of this
type, and in design identical with this new lens of Zeiss, although
in fact the oil-immersion front lens was applied to a g-in. dry
objective. This lens I have had in constant use since then, and
have exhibited it on various occasions. I am a little surprised
to learn from Mr. Nelson's paper that I have not actually shown
it to him. It was catalogued for exhibition at South Kensington
at the time of the Optical Convention, and although there was a
difficulty about the space, so that the lens itself was not actually
set up there, the following description of it appears in the
catalogue :
" The use of oil immersion has hitherto been confined to
objectives of the l/8th-in. and l/12th-in. class under an im-
pression, which proves to be mistaken, that oil immersion secures
no particular advantages when applied to objectives of lower
power. The model is a |-in. dry lens fitted with a supplementary
lens of rather less than hemispherical angle, mounted so that the
516 J. W. GORDON ON A "NEW OBJECT GLASS BY ZEISS.
centre of the sphere lies in the object. The spherical surface,
therefore, produces no refraction, and its addition to the optical
system involves no change in the correction of an objective
adjusted for viewing an uncovered object. The abolition of the
top surface of the cover glass by oiling on the supplementary
front lens produces an increase of 50 per cent, in magnifying
power, and a commensurate increase in light-gathering power.
The catoptric haze produced by internal reflection from the front
face of the permanent front lens sinks into comparative in-
significance, and a g-in. dry lens is converted into a 3 -in.
immersion system of much improved defining power."
Two things may be added to this description :
(1) The numerical aperture of this lens as it stands is 0*54.
(2) It was intended that this front lens should be made
adaptable not only to the g-in. mentioned, but also to my |-in.
objective, in which case it would have yielded exactly the
combination which Mr. Nelson now describes. It was found,
however, that the front lens was a little too thick for use with
a I -in. objective, and consequently I have never been able to
adapt it to a higher power than the g-in. The principle, how-
ever, upon which the construction is based is clearly set out
in the extract above given from the catalogue of the Optical
Convention, and if Messrs. Zeiss have given any attention to
that document, it is obvious that for upwards of a twelve-month
past they have had the benefit of the suggestion so made public.
It is, of course, quite possible that the Jena House have paid no
attention to the catalogue of the Optical Convention, but have
worked out the theory of this new objective for themselves.
Even if we suppose that they have profited by the publication
which has been placed at their service, we must still concede
to them the merit of being the first to turn to account a sug-
gestion which has been equally at the disposal of our own
British manufacturers.
While I am on this point I should like to communicate to
the members of the Club a further development of this principle.
In consequence of the failure of this lens, as I have explained,
to serve the purpose as an oil-immersion front lens for my |-in.
objective, I was led to provide myself with another, of which
a sketch appears as fig. 1. It is adapted, as will be seen, to
be mounted, not on the dry objective, but on the cover glass
J. W. GORDON ON A " NEW " OBJECT GLASS BY ZEISS. 517
of the specimen. A shallow brass ring enables the observer
to move it about, and place it wherever he pleases on the
specimen, so that it exactly covers the spot which he desires
to examine. If, then, he places this specimen with this sup-
plemental lens in position under his dry objective, he gets,
in effect, precisely the combination which Mr. Nelson describes.
It is to be observed that in this combination it is not necessary
to make any corrections for colour or for spherical aberration,
because if the lens is of the right thickness, so that the centre
of its spherical surface coincides with the focal point, then the
incident beam passes the air-glass surface of the lens without
refraction. It passes, therefore, without aberration of any kind,
and the dry lens is in exactly the same position as if it were
applied to a dry object. In the case of a dry lens which is
corrected for the cover glass this would, of course, be a dis-
z
COVER CLASS.
BRASS RING.
-LENS. "--GLASS BASE.
Fig. 1.
advantage, but a dry lens which is adapted to be used upon
a dry object will give, under these conditions, a perfect image.
That is, no doubt, the principle of construction of the Zeiss lens
which Mr. Nelson describes.
To complete the description of this new adjunct : The brass
ring is mounted upon a thin cover glass which, in its turn,
carries the spherical lens cemented at its centre. Theoretically,
of course, the lens and cover glass should be of the same glass,
but in the case of my model I have used what I had ready to
hand, without being punctilious upon this point.
Such a supplemental lens is for some purposes a very con-
venient adjunct to the ordinary microscope. In the first place,
it puts the microscopist in possession of a system such as Mr.
Nelson has described, at extremely small cost, for, of course, this
appliance, consisting simply of a small brass ring, a cover glass,
and an uncorrected spherical lens cemented together, can be
produced at almost infinitesimal cost. It is then available for
518
J. W. GORDON ON A " NEW " OBJECT GLASS BY ZEISS.
use with any dry lens as required, of which it will increase the
magnifying power by 50 per cent, with a proportionate increase
in the amount of light collected, so that the enlarged image loses
nothing in brightness. In this sense it increases the resolving
power of the system, inasmuch as it increases the scale upon
which all the details are shown.
That, however, is but the least part of its merit. If that were
all it would only constitute a |-in. objective the equivalent of
^ in. ; I in. the equivalent of i in., and so on. What is very
much more important is that it gets rid of the top light reflected
down upon the surface of the object by the upper surface of the
cover glass. It does not seem to be at all generally understood
by microscopists how much resolving power is lost by reason of
the fog produced by these reflections from the upper surface of
COVER GLASS.
Fig. 2.
the cover glass. When we are examining an object like a
diatom by transmitted light and producing, by means of that
transmitted light, what the late Prof. Abbe used to call an
absorption image — that is to say, an image in which the face
presented to us by the object is seen in shadow — it is of first-rate
importance that the shadows should not be illuminated by top
light. A dry cover glass sends back upon the upper surface of
the object a large amount of such top light, thereby obscuring the
contrast by virtue of which the image is seen. Furthermore, if
the object is not in actual optical contact with the glass, there
is sure to be a reflecting surface between the glass and the
mounting medium which is illuminated by this top light and
again produces a brilliant haze through which the object has to
be viewed. The diagram fig. 2 will serve to illustrate these
points. Here a section is taken through the cover glass with
J. W. GORDON ON A " NEW " OBJECT GLASS BY ZEISS. 519
its upper surface dry and through the mounting medium and
the specimen. The specimen is represented by two opaque
objects, one in optical contact with the under surface of the
cover glass, the other at some little distance below the surface,
so that there is no optical contact in the second case. A line
marked R indicates how light from the condenser is reflected
downward from the upper surface of the cover glass, and then
upward from its lower surface so as to produce a luminous haze
overspreading the field except where optical contact between the
specimen and the cover glass does away with the second reflection.
It will be seen that the shadows produced by transmitted light
are attenuated by this reflected light wherever the object does
not come into optical contact with the cover glass. Similar
considerations show that the light which is internally reflected
from the upper surface of the front lens and again internally
reflected from the lower surface of that front lens gives rise to
a similar catoptric haze which is diffused over the whole field and
serves therefore to attenuate the absorption image even of these
objects which are in optical contact with the cover glass.
Now all this mischief, so far as it is due to internal reflections
in the cover glass, is avoided by the use of a spherical lens
cemented on to the cover glass, since by its means all such
internal reflection is abolished. From this cause chiefly results
the improved definition which gives to these immersion objectives
of low angle their comparatively high resolving power.
Besides its extreme cheapness, this new form of immersion
lens has the merit of serving as a finder. For example, an
observer who wishes to keep a particular object — say a culture —
under observation for a length of time can cement one of these
supplementary lenses in place over the spot occupied by his
specimen and put the specimen away in that condition. When
next he goes to examine it he will find it without the least
difficulty, for all that he has to do is to place his slide on the
stage of his instrument with this cemented lens in the axis of
collimation. It is possible, now that Messrs. Zeiss have dis-
covered and advertised the value of low-power immersion objec-
tives, that this very simple appliance may also find a manufacturer.
Hitherto, I have not succeeded in interesting any of our
manufacturers in it, possibly because the market price would
necessarily be small. As against that consideration, however,
520 J. W. GORDON ON A " NEW " OBJECT GLASS BY ZEISS.
it may be pointed out that bacteriologists would probably find it
worth their while to buy this piece of apparatus in considerable
quantities, if it were to be had at a reasonable price, since it
would very considerably facilitate their labour where a series
of observations have to be made upon one given specimen of
culture.
Journ. Qutkett Microscopical Club, Ser. 2, Vol. XII., No. 76, April 1915.
521
MICROSCOPICAL METHODS IN BRYOLOGICAL WORK.
By G. T. Harris.
{Read March 23rd, 1915.)
If any apology is needed for bringing before the Quekett
Microscopical Club a subject that may only be of interest to a
limited number of its members, I would find it in the fact that
some years ago the Club had in Dr. Braithwaite a president
whose supreme interest was bryological work. As long as
bryology interests and attracts scientific workers will Dr. Braith-
waite's name be held in honour, and his magnificent British
Moss Flora rank with the splendid natural history monographs
published during the nineteenth century.
It is easy to understand that mosses do not appeal very
strongly to the microscopist per se, as the work to be done
amongst them is more or less systematic ; they offer no
problems of resolution (that I know of), their development is
quite well understood, and even an infatuated bryologist would
be reluctant to advise an excursion amongst them in search of
"display" objects. In spite of these drawbacks, however, it
would be difficult to find a class better adapted to the require-
ments of the microscopist desirous of confining himself to some
special group, and more especially to microscopists resident in
large cities. Mosses may be gathered when opportunity permits,
dried and stored for months, indeed years, and yet resume their
original appearance when moistened previous to examination.
Sufficient material for a whole winter's work can easily be
collected during the annual vacation, and it is unnecessary to go
to any particular district, unless of course special forms are
required. Even an orchard is favourable ground, especially
when the trees reach that desirable standard " old and crusted."
Winter is par excellence the moss season, they then practically take
over the country-side. There is no overgrowth of phanerogamous
plants to conceal their presence ; the hepatics may in some
districts set up a rival claim for notice, but as many bryologists
are also hepaticists this is not a disadvantage when collecting.
Journ. Q. M. C, Series II.— No. 76. 36
522 G. T. HARRIS ON MICROSCOPICAL METHODS
They are not in the least particular where they grow, any
ineligible site will do for them. The only disturbing factor in
the life of a moss that I am acquainted with is an east wind.
They will stand all the indignities that man in the shape of an
agricultural labourer can inflict upon them, but with an east
wind they make no manner of compromise, they shrivel up ; and
how tightly a moss can screw itself up must be seen to be
believed. Nothing more unlike the beautiful silky, pinnate
stems of Hypnum sericeum can be imagined than the same stems
showing their disgust with an east wind. It is obvious that moss
collecting in an east wind is more or less of a failure.
The earlier bryologists relied mainly upon herbarium sheets
for the preservation of their specimens, and, while admitting that
the herbarium is an essential in systematic work, I incline to the
opinion that insufficient attention has been paid to the formation
of what may be described as the micro-herbarium. Herbarium
sheets at the best can give only the general habit of the plant,
and, indeed, in a very large number of species even this is so
poorly preserved as to be practically valueless. The specific
differences are dependent upon microscopic structure, and either
mounted slides or fresh material must be referred to before the
species can be named with certainty. Thirty years ago specific
distinctions were largely dependent upon general habit and such
simple low-power observations as the presence or absence of the
so-called " nerve," its length, and the nature of the leaf margin.
Hence we find Berkeley contenting himself with the brief remark
that an objective of one-third of an inch is the most convenient
for examining the leaves, while low powers are sufficient for the
determination of genera and species. Since then bryology has
become more and more a microscopical study, and Berkeley would
probably have been aghast had he been told that almost in his
own day specific determination would be to a considerable extent
a matter of cell-measurement. Even Braithwaite kept outside
the region of the micron. It can be seen that the modern
bryologist has of necessity to be at least a fairly competent
microscopist, and that the time has come when the carefully
displayed sheets of the moss herbarium mean very little to the
critical systematist. No bryologist in the present day would care
to decide upon the specific names of a large number of our
British mosses from an examination in the field, even with the
IN BRYOLOGICAL WORK. 523
aid of a good lens. The inevitable result is that the micro-
herbarium becomes increasingly more important to the systematic
bryologist.
The collection of slides the Quekett Microscopical Club has
done me the honour of accepting is fairly representative of the
kind of slide useful to the bryologist, although I have, in the hope
of proselytising amongst the members, made it more popular than
would otherwise have been the case. There is no question of
making attractive mounts with the bryologist, even if mosses lent
themselves to such a proceeding. By the time the modern
student of mosses has decided whether some moss is a sub-species,
variety, form, or hybrid of a certain species, he is usually beyond
the ambition of making an attractive mount of it, and merely
desires to see it safely under a cover-glass for future reference.
From the student's point of view the collection would undoubtedly
have been of far greater usefulness had it consisted of series
showing varietal differences in such difficult forms as exist
amongst the Harpidioid Hypna, but the general interest of such
a collection would have been nil. The casual excursionist into
the moss world is more concerned with general impressions than
varietal distinctions, and the microscopist who values his whole-
some outlook on Nature will leave such sections as the Harpidioid
Hypna to its creators.
To the confirmed microscopist I fear the class Musci can never
be very attractive, as it is difficult, except in a limited degree, to
obtain clean, immaculate slides. The cleaning of such species as
Fissidens exilis, Pottia minutula, etc., which not only live on
tenacious clay formations, but succeed in covering themselves
entirely with it, is appalling if conscientiously carried out, and
usually quite fruitless, as by the time the clay has been removed
the specimen is in fragments and not worth mounting. Hence
cleanliness is next to uselessness in bryological work, and a really
useful collection of moss slides occupies a debatable position
between the geological and botanical kingdom i. I mention this
in case your Hon. Curator is puzzled as to which kingdom some
of the slides are intended to represent. A coi siderable amount
of soil usually adhering to the specimens may be got rid of by
prolonged soaking, repeatedly changing the water, and very
considerable help is got by strongly acidulatiag the water with
hydrochloric acid ; especially is this the case in calcareous
524 G. T. HARRIS ON MICROSCOPICAL METHODS
districts. Boiling the specimen may help matters if it is thought
the moss is robust enough to stand the treatment, and some
species certainly will. But the application of a stiff camel-hair
pencil is always necessary to dislodge the particles that adhere
in spite of all soaking and boiling. And when all has been done
there is always the victorious residuum to jibe at one's efforts.
Many species are so fragile that any attempt at cleaning beyond
the most superficial seriously injures the specimen ; such is the
case with those species having highly papillose leaves — in fact
such leaves are rarely found perfect, so easily do the papillose
cells break away from each other. It is obvious that the
question of cleaning the material is a serious tax on the time of
the bryologist, and that there really is a valid excuse for his
mounts not being the immaculate objects usually achieved by
the microscopist.
Another cause contributing to indifference in bryologists'
slides is the necessity that exists for accomplishing a considerable
amount of work in a short time. The busy systematist spends so
much time in the examination and naming of his specimens that
the margin of time available for the preparation and mounting
of slides to illustrate his species is too meagre to allow of
deliberate and painstaking care, hence a slide which* would be
better for remounting is allowed to pass if it shows clearly the
desirable features. It is without doubt the need for the minimum
of trouble in mounting that has caused the majority of bryo-
logists to rely on glycerine jelly for obtaining their mounts. At
least I have ascertained that many quite eminent workers do
rely on this medium, and from what I have heard I fear to their
undoing. Some years ago, by great industry, I amassed a
considerable collection of slides illustrating the Hypnaceae,
spending the leisure hours of an entire winter in doing so, and
in twelve months' time I had the pleasant experience of washing
them off, as slides so illustrative of lacunae and every phase of
cavity were of no use to me. As I had slides mounted in
glycerine jelly perfectly good after a lapse of six years, it was
obvious that it was not necessarily an unreliable medium, and as
I believe it to be the most convenient medium for general work
in bryology I give the following hints to novices for what they
may be worth. In the first place, the jelly itself must not be
made with a hard gelatine. I used Drescher's emulsion gelatine,
IN BRYOLOGICAL WORK. 525
which is an extremely clear but hard gelatine, and this was the
principle cause of my disaster. The jelly must contain a good
proportion of glycerine. Kaiser's formula appears to be a very
good one if home preparation is in view, as it does not set hard.
I have slides six years old mounted with it which have suffered
no deterioration. The object to be mounted should be soaked for
a considerable time in equal parts of glycerine and water (in my
own work they always have twenty-four hours) ; unless the
structure of the object is thoroughly permeated with the dilute
glycerine, lacunae are sure to develop by subsequent absorption.
My own experience leads me to the conclusion that a point of
great importance in using glycerine jelly so as to ensure reliable
mounts, is to avoid mounting the object with the jelly at a high
temperature; it should be used at just about the melting-point.
If the temperature is high, subsequent contraction is considerable
and cavities around the object are not unlikely to make an
appearance later on.
Another point where many mounters err, especially bryolo-
gists, is in applying considerable pressure to the cover-glass
until the jelly has set, thus pressing out the bulk of the jelly and
leaving only a thin film between the slip and cover-glass. It is
very nice to have a leaf mounted perfectly flat so that the cells
can be studied from apex to base without focusing down through
the convexity of the leaf ; but such slides are seldom permanent.
The amount of jelly should be sufficient to cover the object ; and
it is easy, when constantly using jelly, to guess just about the
amount that will cover the object and spread to the edge of the
cover-glass when it is placed in position. When the jelly has
thoroughly set, if any has escaped beyond the edge of the cover-
glass it should be washed away. Personally, I lay the slide
aside for about twenty-four hours after mounting, then give it a
good scrubbing with a moderately stiff tooth brush under a jet of
water. This frees it from all glycerine outside the cover. The
slide is then ringed with a plain solution of good hard gelatine,
the strength of the solution being immaterial so long as it is not
a weak one. When this has set, which it will do quite quickly,
it is brushed over with a 10 per cent, solution of chrome alum.
At firs-t I used formalin, but found that its indurating action was
so great that the ring of gelatine split and peeled off. Chrome
alum toughens rather than hardens the gelatine. In its present
526 G. T. HARRIS ON MICROSCOPICAL METHODS
state the slide is perfectly safe for months, and may be finished
at some convenient time subsequently. The finishing consists in
ringing with old gold size, coat after coat, with intervals to allow
for hardening.
I have been most desirous of making glycerine jelly mounting
a reliable process, owing to its great usefulness in rapidly mount-
ing reference slides of leaves and small species of moss. Unfortu-
nately I have received several bad shocks in my own work, and
in reports from other bryologists, and I must frankly confess to a
grave misgiving in asking the Quekett Microscopical Club to
accept slides mounted in this medium. Only the fact that I
believe some of the principal pitfalls to have been traced and
overcome has permitted me to include any at all. Certainly for
a long time past now I have been immune from my former
perennial crop of lacunae and cavities. In all cases the date of
preparation has been marked on the slides, and if they are not an
example at least they will be a warning.
Unless the object is of an appreciable thickness the film of
jelly necessary to cover it will not be so thick as to need any
support ; but if some species, or portions of large species, are
mounted with their capsules the amount of jelly necessary may
need some support at the edge to keep the cover-glass even. A
convenient way of doing this is to use a ring of silver wire about
the diameter of the cover-glass and of a thickness proportioned to
the object. Practically a thickness of 23 B.W.G. meets all needs,
and I confine myself to this thickness. Silvered wire is easily
and quickly prepared by taking copper wire of the desired thick-
ness, thoroughly cleaning it from all grease, and immersing it in
silver cyanide solution. It can then be kept on a reel, and cut
off as required. The ring needs no attaching to the slip, as the
gelatine holds it in position ; but it may be slightly flattened by
hammering.
Farrant's medium probably comes next to glycerine jelly in
usefulness to the bryologist ; it is very convenient to use, and, of
course, allows of great deliberation in arranging the object, re-
moving such undesirable matter as can be removed, and it gives
good transparency to incrassate cells. For peristomes, which
require to be examined by transmitted light, it is excellent,
though the fragile endostomes of some species are made too trans-
parent by it.
IN BRYOLOGICAL WORK. 527
When my loss of the twelve dozen type slides of the Hypnaceae
shook my faith in glycerine jelly I made experiments in search of
a substitute, and found an extremely good one in copper acetate
combined with glycerine. The formula is given in Squire's
Methods and Formulae, but is not referred to any author. It
has the advantage of being also a fixing agent :
Copper acetate
Mercury chloride
Acetic acid .
Glycerine
Distilled water
02 gramme.
0-4 „
0-2 c.c.
25-0 „
25-0 „
This gives a certain amount of transparency to the cellular
structure of the leaves, but it naturally imposes much more
labour on the mounter, and is better suited to the microscopist
who merely wants mosses for general interest.
A large number of mosses are so minute that they are quite
useless as herbarium specimens, and the only satisfactory way is
to possess them mounted as microscopical slides ; such species are
Fissidens exilis, F. pusillus, F. viridulus, the majority of the
species of the genera Pottia, Ephemerum, Pleuridium, etc.
The leaves of these small species are usually very transparent
and do not require to be made additionally so by glycerine, even
when dilute. Acetate of potash is an admirable mountant for
such forms, especially when containing a trace of copper acetate.
The following formula has given me satisfaction, it is based on
the one Prof. G. S. West recommended for algae :
Copper acetate O05 gramme.
Potassium acetate 10 ,,
Water 25-0 c.c.
Formalin, 2| per cent, solution, may also be used for these
minute, transparent species, but in slides that have been mounted
a number of years I have noticed that the formol sometimes
precipitates, so that I have been reluctant to use it to any con-
siderable extent. On the other hand, many slides in formol
appear to have kept perfectly, so that much may depend on the
sample of formol used.
With leaves of such species as Andrea Bothii, which are
extremely dark in colour and of leathery consistency, it is im-
528 G. T. HARRIS ON MICROSCOPICAL METHODS
possible to examine the structure satisfactorily in its normal
condition, and they are best treated in a solution of caustic soda
or potash, as recommended by Dr. Braithwaite. This renders
them flaccid and defines the cell structure. They should, of
course, be washed well before mounting, and glycerine in some
form is desirable with them as with all dense-leaved species.
The species of Andreaea are typical of the difficulties that con-
front the bryologist in attempting to get satisfactory permanent
mounts. They are deep red or black-brown in colour, very dense
and cartilaginous in texture, extremely brittle and abominably
dirty. It may be remarked that the colour of moss leaves,
which is usually some shade of green, is a matter of minor
importance to the mounter, hence it can be left out of considera-
tion in choosing a medium for mounting. The bryologist mounts
the leaves altogether for shape and cell-form, as upon these
depend in a great measure the determination of the species.
Usually the colour disappears in the course of a few months, but
curiously enough in the same medium the green colour of closely
allied species will remain fairly good. Very often saprophytic
algae will retain their colour perfectly, while the moss has
altogether parted with it.
There appears to be no necessity for " fixing " the specimens
before mounting ; but with leaves of comparatively delicate struc-
ture it is often advantageous to do so unless the mounting medium
contains a fixing agent, and I have had very good results with
the complanate branches of such species as Plagiothecium elegans
and Plagiothecium depressum by fixing them in picric acid before
mounting in glycerine jelly, the picric being washed out previous
to mounting. With such a species as Plagiothecium depressum,
which bears very characteristic bunches of deciduous flagellae on
its branches, every care has to be exercised to avoid detaching
the flagellae, whose particular mission it is to become detached
with the slightest provocation. Such is the case with many
species of Tortula, the leaves of which bear characteristic gemmae.
The extremely beautiful bunches of gemmae at the apices of
Ulota phyllantha, and the scattered gemmae on the leaves of
Orthotrichum Lyellii, are other instances. It is only the novice
who will attempt to "clean" such leaves; the confirmed bryologist
is too thankful to get the leaves mounted with the appendages
adhering to worry over a small amount of adventitious matter.
IN BRYOLOGICAL WORK. 529
The air contained in the cork-like cells of Leucobryum glaucum,
and other species with inflated cells, is often very difficult to dis-
charge. Boiling gets rid of a certain amount, especially if the
leaves are left in the de-aerated water for a day or two, with re-
boiling at intervals. Obstinate cases require exhausting with an
air pump. The leaves of the Sphagnaceae are especially difficult
if the moss is once allowed to become thoroughly dry and the
cells filled with air. I make a point of mounting these as soon
as collected, or, at any rate, of keeping the stems saturated with
water until I can attend to them. Bryologists attach very great
importance to the basal areolation, and it is necessary that the
leaves should come away from the stem quite complete and un-
injured, but it is not at all a simple matter to detach the leaves
from the stems previous to mounting them. With strongly
decurrent leaves, such as exist in Mnium stellare and in some
Hypna, it is almost impossible to obtain perfect specimens, and
it is better to remove several of the adjacent leaves, and mount a
portion of the stem with the leaf in situ. Generally, the most
satisfactory way of removing a leaf is to take hold of the apex
with a fine pair of forceps, and, holding the branch with another
pair, very gradually to strip the leaf from the stem in a down-
ward direction. Mosses with filiform stems and distant leaves
such as Amblystegium serpens, can be studied by mounting the
stem with the leaves attached. The strongly falcate and circin-
nate leaves of Harpidioid Hypna are very unmanageable, and I
usually strip a considerable number of leaves from the stem, and
mount the lot as a " spread " slide, trusting largely to luck to
arrange some of them in a suitable position for examination.
This is obviously a reckless method, but it answers very well.
A certain amount of section cutting is necessary to the syste-
matic bryologist, apart from any histological investigation. The
leaves of the Polytrichaceae, for instance, have the surface
covered with longitudinal lamellae consisting of rows of upright
moniliform filaments. Prof. Lindberg was the first to point
out that these formed a valuable aid in diagnosing the different
species, as the transverse number and shape of the terminal cell
differ in each species. The only way in which they can be satis-
factorily examined is by means of a transverse section.
The section Aloidea of the Tortulaceae also has lamelliferous
leaves, of which sections are necessary. The quickest and
530 G. T. HARRIS ON MICROSCOPICAL METHODS
simplest way is to cut the sections in an ether-freezing microtome,
and extremely thin sections are not demanded, but as the sections
must be cut at right angles to the axis of the leaf, some care
in orientating the leaf has to be taken. Sections of stems are
also required in determining species of Sphagnaceae, but these
are, of course, a simple matter.
In dealing with the capsule of the moss two methods of
mounting may be employed for the study of the peristome. It
may be mounted dry as an opaque object, or in some medium
as a transparent one. Mounted dry and illuminated with
reflected light the peristome is the only concession the moss
world makes to spectacular effect. For purposes of study, how-
ever, the limitations of this method are great, and the student is
forced to adopt transparent mounting. At the same time dry
mounts of some peristomes are quite useful to the bryologist in
getting at the general appearance ; the sulcae of the Orthotrichum
capsule and the cilia of its endostome are quickly and satisfactorily
exhibited as an opaque object under the binocular microscope.
For anything like detailed study, however, the peristome must be
mounted as a transparent object. A good deal depends upon
getting the capsule in the right condition. It should be quite
ripe, so that the touch of a needle at the junction of the operculum
with the capsule will liberate the lid and enable the peristome
to unfold without injury. If the lid has to be forced away some
of the teeth of the peristome usually go with it. To prepare it
for mounting, the capsule may be severed transversely about the
middle, then a longitudinal slit made through the annular ring
and that portion of the capsule wall adhering ; this permits of the
peristome being spread out flat. The spores require washing
away, though it is an advantage if some of them adhere to the
teeth, as they often afford valuable specific characters. If the
capsule has already shed its spores when gathered, but is not
dilapidated, it is often in a very favourable condition for mount-
ing, and in those mosses with a double peristome the endostome
can often be detached and mounted separately from the exostome ;
this enables the cilia so often present in double peristomes to be
studied to the best advantage. When the cut peristome has been
laid flat and judiciously cleaned it should be subjected to a cover
slip and spring clip for a day or two, glycerine and water being
run under by capillary attraction. The annular cells are usually
IN BRYOLOGICAL WORK 531
so elastic that some difficulty is found in keeping the peristome
flat when it is mounted unless pressure has been previously applied.
Glycerine jelly or Farrant's medium are the most convenient
mountants. There is really no particular reason why the peristome
should be mounted in its entirety, as a sector of it serves all useful
purposes and is very much more easily managed ; that is to say,
there is no additional knowledge gained by mounting the whole
thirty-two teeth of a double peristome when a sector embracing
four each of the outer and inner teeth will enable all structural
details to be made out. The tubular teeth of the Tortulaceae can
only be mounted en bloc ; the basal membrane is the point of
interest, and so long as this can be clearly made out the rest does
not matter.
In some species the teeth of the peristome are extremely
fragile, and it is rarely possible to get satisfactory mounts of
them if one relies on finding a perfect specimen in a chance
gathering. I believe the only way is to bring home unripe
specimens and carefully ripen them under observation, so that
the capsule can be mounted as soon as the ripe operculum falls.
The capsules of the Orthotrichaceae bear very important char-
acters in the presence of stomatic cells. These are of two forms ;
in the one they are seated in the cuticle only and are " superficial,"
in the other they are buried in the wall of the capsule and are
" immersed." To get a good view of them the capsule is slit up
and the spore ^ac removed. The capsule is then spread out on
a slide, cuticular side uppermost, and mounted in glycerine jelly.
The stomata are said usually to be found in the lower half of
the capsule, and they are certainly always found there in the
books ; but occasionally nature seems to ignore her own boundaries,
for I have seen them scattered here and there over the capsule,
As I have previously stated, a student's collection of slides
would be no incentive whatever to any one to take up the study
of mosses. At the same time I can imagine no more valuable
collection than a reference series of slides of closely allied species,
and species subject to wide variation. The determination of
species and varieties in the moss flora has become a matter of
extreme difficulty, thanks to the efforts of specialists in various
groups, and even an advanced worker is glad of anything that
looks like finality. Fifty years ago English bryologists con-
sidered themselves well served with ten species of Sphagna, the
532 G. T. HARRIS ON MICROSCOPICAL METHODS
separation of which was no great strain on one's mental powers.
At the present time it is useless to touch the group unless you
are prepared to distinguish between at least forty species, with
an average of four varieties each. Of Sphagnum acutifolium
alone Warnstorf describes sixty varieties, and I believe that very
few even critical bryologists would care to rely on their own
diagnosis of them. It will be seen from this how valuable an
authenticated collection of slides would be to the bewildered
student.
It will perhaps be desirable to state that the nomenclature
adopted in naming the slides is that of the second edition of
Dixon's Student's Handbook of British Mosses. 1 believe that
Dr. Braithwaite's magnificent monograph is in the library of the
Quekett Microscopical Club, and my first intention was to take
that as my guide j but Dixon's Handbook is now so generally
used, and is so compact, that it would probably be the book
selected by any one who decided to take up the study of the
mosses ; and I may say that the critical comparisons in it
between closely allied species are extremely useful to the student
working alone.
IN BRYOLOGICAL WORK. 533
Notes on a Collection of Slides of Mosses.
Polytrichum formosum.
Sections of a leaf cut to show the jointed appendages that
constitute the lamellae. These appendages are of great use in
determining the species, as the form of the terminal cell, the
number of cells in each appendage, and the average number of
appendages in the transverse section differ with the species.
Ceratodon purpureus
A common moss in dry woods, on sandy banks, etc., but also
a very polymorphous moss. In spite of considerable leaf
variation, however, a distinct and constant feature is the
recurved margin, becoming plane immediately below the apex,
which is usually toothed. The characteristic annulus is well
shown in the slide.
Dicranum majus.
A fine moss usually occurring in mountainous woods. The
common and variable Dicranum scoparium in some of its forms,
which are chiefly barren, approaches it very closely. Dicranum
majus, however, bears a multiple number (2-5) of setae from
one perichaetium. Both species belong to the section Eu-
Dicranum, which is characterised by the leaves having lateral
pores connecting the cells in the lower part of the leaf.
Leucobryum glaucum.
An interesting moss, the leaves of which are well worth
careful examination. The chlorophyll cells are masked by an
outer layer of hyaline, inflated corky cells communicating by
pores. The greater portion of the leaf is composed of the nerve.
Cardot has monographed the genus, see his Recherches Anatomiques
sur les Leucobryacees. It is a not uncommon moss on dry, turfy
ground, but the fruit is very rare, and according to my experience
found chiefly when the moss grows in quite damp localities. A
curious state of the moss occurs in dry woods in which it forms
small rounded cushions, quite detached from the ground, and
534 G. T. HARRIS ON MICROSCOPICAL METHODS
easily transported by strong winds or contact with moving
objects. The leaves are easily detached and often bear at their
tips tufts of radicles which give rise to new plants.
Fissidens exilis.
One of the smallest species of the Fissidentaceae and readily
known by its non-bordered leaves.
Fissidens viridulus.
Known from the preceding by its leaves having a narrow
border to them, but the variety Lylei has the border wanting
except on the sheathing laminae.
Fissidens algarvicus.
I am able to include a specimen of this new British moss through
the kindness of Mr. G. B. Savery, its discoverer in England.
It comes near Fissidens pusillus, and so far has only been found
in two localities, Silverton in Devonshire, where Mr. Savery first
discovered it, and near Cheltenham. It is characterised by its
narrow acute leaves with rather strong and narrow border.
Fissidens bryoides.
An extremely common and variable species, the forma in-
constans was originally a separate species, but is now generally
considered to be merely a " form " of F. bryoides. As will be
seen from the two slides, the difference is considerable in general
appearance, and I have found the form inconstans to be little
subject to variation from widely different localities.
Rhacomitrium lanuginosum.
This is the largest British species of the Grimmiaceae, and
often covers immense tracts of mountain moorland with great
masses. The hyaline and papillose serrated leaves are very
beautiful.
Hedwigia ciliata.
Another inhabitant of dry, rocky localities, with, as is usually
the case with such mosses, hyaline apices to its leaves. The
IN BRYOLOGICAL WORK. 535
perichaetial bracts are ciliated, as may be seen in the slide,
whence the specific name.
Pottia lanceolata.
The Pottias are usually without peristomes, but the present
species is a notable exception, in that it possesses a highly
developed one.
Pottia truncatula.
A gymnostomous form readily known by the truncate capsule
with wide mouth, and by the columella being attached to the lid
and falling with it.
Barbula lurida.
This is essentially a calcareous-loving species, and is considen d
very rare in fruit. The peristome is very fragile, and it is
difficult to obtain good specimens.
Ulota phyllantha.
Readily known by the clusters of brown gemmae borne at the
apices of the leaves. The fruit is extremely rare, and has only
been found once or twice in Eno-land.
i»4
Orthotrichum Lyellii.
This also may be readily known by the brown gemmae, which
in this species are scattered generally over the surface of the
leaves. It rarely fruits.
Orthotrichum diaphanum.
The capsule wall of this species shows the "immersed" stomata,
and should be compared with the slide of Orthotrichum affine,
which shows " superficial " stomata. The two forms are very
useful in diagnosing the species of this difficult genus. The outer
" superficial " cells are well shown in the slide, and the reniform
" guard " cells may be brought into view by focusing down
through the superficial cells.
536 G. T. HARRIS, MICROSCOPICAL METHODS IN BRYOLOGICAL WORK.
Brachythecium rutabulum.
One of the commonest and most variable of the British mosses.
The type is not difficult to recognise, but the varieties with very
acuminate leaves are difficult to determine, especially when
barren, as they often are.
Hypnum cupressiforme.
This again is a very variable form, and its varieties differ
widely from the type. The var. resupinatus has had specific
rank from many authorities, but it certainly differs no more
from the type than does the var. jUiforme.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., A'o. 76, April 1915.
537
PROCEEDINGS
OF THE
QUEKETT MICROSCOPICAL CLUB.
At the 501st Ordinary Meeting of the Club, held on October 27th,
1914, the Vice-President, Mr. D. J. Scourfield, F.Z.S., F.R.M.S.,
in the chair, the minutes of the meeting held on June 23nd were
read and confirmed.
Messrs. Samuel Ernest Loxton and W. Beattie were balloted
for and duly elected members of the Club.
The list of donations to the Club was read, and the thanks of
the members voted to the donors.
Two series of Dr. Sigmund's histological preparations with
descriptions and sixty-one slides were added to the Cabinet.
The Chairman read a letter conveying the information of the
death of Dr. Arthur Mead Edwards, of Newark, New Jersey,
U.S.A., which took place on September 13th, 1914. Dr. Edwards
was the oldest honorary member, having been elected in January
1868. He was at that time President of the American Micro-
scopical Society of New York. At his death he was seventy-
eight years of age. His chief microscopic work was in the
study of the Diatomaceae. His communications are still re-
membered by some of the older members.
The. report from the Club's delegate — Mr. C. F. Rousselet,
F.R.M.S. — to the conference of the delegates of the corre-
sponding societies of the British Association at Havre was read
by the Secretary. The Congress began on Monday, July 27th.
Mons. A. Gautier, the President, welcomed the members, and
delivered an address. On behalf of the English members, Sir
W. Ramsay addressed the meeting in French. On Tuesday there
was a conference of delegates in the Town Hall. Sectional
meetings took place on that day and on Wednesday. On Thurs-
day, the 30th, an excursion up the Seine as far as Rouen, visiting
various historical places on the way, was made. On Friday
meetings were held, but, owing to the threatening political out-
look, were poorly attended. On Saturday, August 1st, the
Government decree of general mobilisation was given, and the
Journ. Q. M. C, Series II.— No. 76. 37
538 PROCEEDINGS OF THE
conference, which had been much hampered by the political
unrest, hurriedly broke up. The Chairman tendered the Club's
thanks to Mr. Bousselet for his report, and congratulated him on
his safe return.
A paper by Mr. A. A. C. Eliot Merlin, F.R.M.S., was read (in
part) on " The Minimum Visible." It commenced : " I have
read with great interest and profit our President's address on
1 Organisms and Origins.' The subject is one that must fascinate
every microscopist, whatever his line of research. In the address
the point was raised respecting the minimum visible, it being
stated that ' it seems impossible to obtain any precise information
as to the size of the smallest particles that can be seen with the
microscope.' Now, setting aside the ultra-microscope, as our
knowledge is very exact and definite indeed on this subject, it
may prove of interest to deal with the question at some length.
As a matter of fact, when a particle properly illuminated is just
visible with a given objective, if the aperture be cut down by
means of an iris diaphragm, placed above the back lens, so that
the particle just ceases to be visible, and the N.A. to which the
objective has been reduced is measured, then the dimensions of
the particle can be exactly ascertained from the antipoint table
published by Mr. Nelson in the Journal of the Royal Microscopical
Society. This antipoint table should prove invaluable when
accurate and minute measurements are necessary."
A recent paper by Mr. N. E. Brown, A.L.S., " Some Notes on
the Structure of Diatoms," was referred to, in which Mr. Brown
stated that he had seen pores on the surface of certain diatoms
which he estimated at 1/200, 000th of an inch in diameter. Mr.
Merlin, examining some of the diatoms under a very perfect
^ apochromat, N.A. 1'4, employed with a magnification of
4,200, readily distinguished these pores, but in them so resolved
believed he immediately recognised Dr. Boyston Pigott's " dark
eidolic dots of interference."
In speaking on the subject of Mr. Merlin's paper, Mr.
N. E. Brown said : " If I understand Mr. Merlin correctly, the
two points in it which call for any remark from myself are
that the structures I have conceived to be pores were discovered
by Dr. Boyston Pigott many years ago, and considered by him
due to interference. I much regret that I have not read Dr.
Boyston Pigott's paper, or I should have referred to it in my
QUEKETT MICROSCOPICAL CLUB. 539
recent notes. But I certainly cannot agree that these structures
are myths without substance. I still maintain that they are
very real structures. I take it that if they were interference
figures, they could only be formed when the dots from which
they are supposed to emanate are regularly placed, equally spaced
and of the same size, also that under different conditions of
illumination or the shifting of the mirror they would alter their
position or form. But this is by no means the case. In most
diatoms the dots are regular in position and size, but on some
portions of the shell of Nitzschia scalaris regular rows of small
dots and diverging rows of much larger dots may be found side
by side, and some of the dots in the diverging rows are often
quite irregularly placed, yet the structures I suppose to be pores
are regularly placed along the middle of the space between the
rowrs in each case, or, where very widely diverging, the row of
pore-structures forks. Also they do not shift their position
under varying conditions of illumination ; they can be seen alike
and in the same position with axial illumination and a full cone
or small cone of light, with annular illumination, with oblique
illumination in one azimuth arranged either parallel with or
transverse to the rows of dots, with either a chromatic Powell
and Lealand or an Abbe, or an achromatic Powell and Lealand
substage condenser. Surely identical myths could not be pro-
duced under all these conditions."
Mr. Ainslie, while pointing out the impossibility of any
detailed criticism until opportunity had been obtained for care-
fully going through the statements, remarked that size alone by
no means determined the limits of visibility : the quality of an
object, its opacity or transparency, and other factors, would
affect the matter. He gave some instances where structures had
been distinctly seen which were far smaller than what is
scientifically considered the minimum required for visibility. On
the proposal of the Chairman, a very hearty vote of thanks to
Mr. Merlin for his valuable communication was recorded.
Mr. Rousselet exhibited under microscopes two species of African
Volvox. These had a somewhat remarkable history. In October
1910 a paper by Prof. G. S. West, of Birmingham University,
was read, in which two new species of Volvox from Africa are
described. One, V. Africanus, had been collected by Mr. It. T.
Leiper, of the Egyptian Government Survey, from the north part
540 PROCEEDINGS OF THE
of Lake Albert Nyanza. The other, V. Rousseleti (named in
honour of its discoverer), was obtained by Mr. C. F. Rousselet on
the occasion of the visit of the British Association to South Africa
in 1905, from a pool formed by the Gwaai River, near the railway-
station. In both cases only asexual vegetative individuals were
acquired, with the result that a complete description could not be
given, in 1913 Mr. Rousselet received from Dr. Jakubski, of
the Zoological Institute of Lemberg University, some tubes con-
taining plankton material collected in German East Africa. In
two of these tubes, among other objects, Mr. Rousselet was
surprised to come across numerous colonies of Vol vox, which he
at once recognised as the same two species already described by
Prof. West. Fortunately, in this case, both species were present
in their various sexual stages, with androgonidia and oospores, as
well as the vegetative colonies. It will, therefore, now be possible
to complete the description of both species. A tragic note is
given to the episode by the fact that Mr. Rousselet returned, as
requested, the tubes and specimens to Prof. Jakubski at Lemberg
early in July; but owing to the war and the occupation of
Lemberg by the Russian Army soon after they should have
arrived, he has not been able to ascertain whether they safely
reached their destination, or what has become of them, or of the
correspondent to whom they were addressed. A vote of thanks
to Mr. Rousselet for his interesting communication was carried
by acclamation.
Mr. W. E. Watson Baker exhibited under a microscope a
mounted specimen of the egg of the Anopheles mosquito and a
very young larva of the same. The organism is rarely found in
these conditions ; but the Secretary mentioned that on two
occasions last year, at excursions of the Club, he had obtained
specimens of nearly mature larvae. In one of the instances he
had been able to feed the creature — they devour some of the
smaller algae — till it pupated, and finally the perfect insect
emerged. The meeting thanked Mr. Watson Baker for his
beautiful exhibit.
At the 502nd Ordinary Meeting of the Club, held on November
24th, the President, Prof. Arthur Dendy, D.Sc, F.R.S., in the
chair, the minutes of the meeting held on October 27th were
read and confirmed.
QUEKETT MICROSCOPICAL CLUB. 541
Messrs. Walter Adams, George Clarendon Hamilton, F. Rear-
don Brokenshire, W. Ludlow Haynes, Alexander McTavish,
W. B. Tindall, Henry Jewell and the Rev. John Bruce Williams
were balloted for and duly elected members of the Club.
The list of donations to the Club was read, and the thanks of
the members voted to the donors.
The President called upon the meeting to pass a resolution
expressing the members' deep regret at the loss they had sustained
by the death of Dr. M. C. Cooke, M.A., LL.D., A.L.S., which
occurred on November 12th at his residence in Southsea.
Dr. Mordecai Cubitt Cooke was born July 12th, 1825, at the
village of Horning, in Norfolk. From an early age dependent
upon his own resources, he was in turn employed as draper's
assistant, teacher in a National school, and lawyer's clerk. As
an assistant in the Indian Museum he at last found congenial
occupation, and on the abolition of that institution he spent some
time at South Kensington Museum. He afterwards joined the
Herbarium at the Royal Botanical Gardens, Kew, and was for
twelve years (1880-1892) in charge of the Cryptogamic Depart-
ment. In 1892 he retired. During this time he incorporated
his own herbarium, which contained 46,000 specimens, with the
existing collection at Kew, as well as the collection of fungi pre-
sented to Kew by the Rev. M. J. Berkeley. His figures of
fungi, mostly coloured, and numbering 25,000 plates, are also
at Kew.
His first important work was the Handbook of British Fungi
(1871), followed by Mycographia, Handbook of Australian Fungi,
and Illustrations of British Fungi (with 1,200 coloured plates).
He was editor of Hardwicke's Science Gossip from its beginning
in 1865 until December 1871. Dr. Cooke, the " father of the
Club," was one of the eleven members who attended the pre-
liminary meeting of the Q.M.C., held on June 14th, 1865, and he
was elected one of its first vice-presidents. He was president in
1882 and 1883, and was elected an honorary member in 1893.
Mr. J. Grundy introduced and explained the great advantages
of a micrometric table by Mr. E. M. Nelson. The table is similar
to logarithm tables, the cross marginal numbers being M and O
respectively. The table gives the value of O x 100/M. M is
the reading of one division of a stage micrometer in the divisions
of the eyepiece micrometer. O is the reading of the object to be
542 PROCEEDINGS OF THE
measured in the divisions of the eyepiece micrometer. To find
the size, take in the table on the M column the number repre-
senting the reading, and the number in that line vertically below
the reading in the 0 line will be the size of the object in microns.
Example : 0*1 mm. of stage micrometer spans 28 divisions of the
eyepiece micrometer. M is then 28. An object measures 19
divisions of the eyepiece micrometer. O is then 19. Utilising
the table, the size will be found at once — viz. 68 //,. Should the
measured division or unit of the stage micrometer be 001 mm., it
is only necessary to move the decimal-point one place to the left
in the final reading, which would give the result in the example
above as 6*8/x. Similarly, if the measured unit of the stage
micrometer had been 1 mm., then it would be necessary to place
a cipher after the figures given in the table ; so in the same
example the object would have been 680 jx., or 0*68 mm. When
the unit of the stage micrometer is 0*1 in., the decimal-point must
be moved three places to the left ; with a unit of 0*01 in., four
places; and with a unit of 0*001 in. five places to the left. In
the example above, the object would measure 0*068 in., 0*0068 in.,
0*00068 in. respectively. The table is published by Messrs. H. F.
Angus & Co., 83, Wigmore Street, London, W., price 3d.
The President said they were very greatly indebted to Mr.
Nelson for this table, and to Mr. Grundy for putting the matter
before them in the way he had done. For his own part he would
welcome anything which saved him from multiplication, and he
should imagine from what he had heard that this was a sort of
ready reckoner for the microscope, and would be extremely useful
to any one who had many measurements to make. He thought
he should find a great use for it in checking his own results by
comparison.
Mr. Ainslie thought that the table promised to be extremely
useful to those who wished to make measurements of minute
objects. If, however, instead of 28 they happened to find 28*7 or
29*3 it would merely be necessary to alter the tube length so that
the stage micrometer below covered a certain value of the eyepiece
micrometer.
In measuring diatoms the tube length must be adjusted, and
having determined that, they must be careful not to touch the
correction collar, as that would at once alter the power of the
objective.
QUEKETT MICROSCOPICAL CLUB. 543
Mr. D. J. Scourfield, F.Z.S., F.R.M.S., read a paper upon a
new Copepod found in water from hollows on tree-trunks, He
stated that in recent years, owing to the endeavour to discover
the life-histories of mosquitoes and other insects supposed to be
connected with the dissemination of tropical diseases, much
attention had been given to the subject, and, according to a
recent paper published by Picado, no less than 250 species of
animals have been found living in this peculiar environment,
forty-nine being new to science. They belonged to almost all
groups of invertebrates ; but naturally insects and their larvae
predominate. Mr. Scourfield pointed out that in tropical forests,
ponds and water on the ground are rarely met with,*this making
it difficult to locate the breeding-places of mosquitoes, etc., until
it was found that incubation took place in water contained in
little cups in tree-trunks and roots. He first commenced to look
for Entomostraca in these situations after reading the celebrated
Fritz Miiller's description of a new Ostracod representing a new
genus, Elpidium bromeliarum, which occurred almost constantly
in association with the Bromeliaceous plants in the forests of
Brazil, and, strangely enough, was to be found in no other
situation. His curiosity was rewarded by finding the remarkable
blind Copepod, Belisarius viguieri, which had not previously been
found in this country. He was able to report that on several
occasions he had found a new Copepod in such little reservoirs of
water on trees in Epping Forest, and up to the present they have
been found nowhere else. The new species evidently belongs to
the Harpacticid genus Moraria, described by T. and A. Scott,
found in Loch Morar, Scotland. Eight species are known,
three of which have been found in the British Isles. He stated
that he proposed to call it Moraria arhoricola, because of its tree-
d welling habit. It is a very small form, the female measuring
only about 1/40 in. in length, of the type of Cyclops, Cantho-
campus and Diaptomus. The genus is peculiarly adapted to
exist in but little water, and, when placed in this element, wriggles
rather than swims. In Mr. Scour-field's experience, it is mostly
found in the early part of the year. He commented upon their
wonderful vitality. In one case, specimens left in a bottle were
kept alive for four years simply by adding a little water from
time to time to make up for evaporation. Mr. D. Bryce asked
if it was known how they are conveyed from place to place, and
544 PROCEEDINGS OF THE
also how they were able to resist the effects of evaporation.
Mr. Scourfield, in replying, instanced that the eggs of such
minute creatures, and also adults, can become embedded and dry,
and remain for a long period in a condition of suspended anima-
tion. Also, that one species of Cyclops and Canthocampus form
a kind of cocoon. As to their distribution he could give no
information.
Amongst other interesting exhibits was a specimen of Stephano-
ceros Eichornii — a wonderful example of the art of mounting, by
Mr. C. F. Rousselet, Curator R.M.S.
At the 503rd Ordinary Meeting of the Club, held on
December 22nd, the Vice-President, Prof. E. A. Minchin, M.A.,
F.R.S., in the chair, the minutes of the meeting held on
November 24th were read and confirmed.
Mr. Frederick Knott was balloted for and duly elected a
member of the Club.
A vote of thanks was returned to Mr. C. F. Rousselet, Curator
R.M.S., for a valuable donation to the Cabinet of twenty-four
slides of Rotifera.
Mr. J. Grundy read a communication from Mr. E. M. Nelson
of great interest to metallurgists. A slide was exhibited con-
sisting of a thin aluminium disc of about 1 mm. in diameter, such
as Mr. Morland uses when mounting selected diatoms, mounted
by itself. When placed under a |-in. or ^-in. objective, and
illuminated by one of the universal condensers, lamp and bull's-
eye, a strong top- illumination is obtained by reflex light from the
front lens. Mr. Nelson states that this idea may prove useful
for the examination of metals, as, instead of using a cubic | in.
for examination, if the end of a wire, say, 1*5 mm. thick and
2 mm. long, was polished and fastened on a slip, the metal might
be investigated probably quite as well as with a larger piece.
He further stated that this idea was by no means new, as it was
first expounded by Rainey sixty years ago, and later by Prof.
B. T. Lowne about 1888, and again more recently by J. W.
Gordon at the R.M.S.
To those interested, the valuable description by Prof. Lowne on
top-lighting by reflections from the front and back of the front
lens of the objective will be found on p. 371, vol. iii., second
QUEKETT MICROSCOPICAL CLUB. 545
series of the Journ. Q. M. C. Mr. Grundy exhibited a slide of
mounted copper which illustrated the same lighting.
Mr. J. Wilson read some notes by Mr. H. Whitehead, B.Sc.,
F.R.M.S., on an epizoic infusorian, Trichodina Steinii C. and L.,
found on Turbellaria. These were found on a specimen of
Mesastoma tetragonum, moving about over the surface of the
body and between the folds. They are a species closely allied to
Trichodina pediculus, which is frequently found on Hydra, but
differs in that T. pediculus has an inner as well as an outer ring
of teeth. The body of T. Steinii varies considerably in shape;
but when at rest it is cylindrical, the diameter at the base being
equal to the height (about 40 /a.), the basal circle of cilia being in
contact with the body of the Turbellarian, while the adoral cilia
form a spiral leading to the mouth. When free-swimming, the
adoral cilia are retracted, while the basal circlet is used for
the purpose of locomotion. The protoplasm contains a number
of small spherular structures, and one or two contractile vacuoles
are to be seen. It possesses a large horseshoe-shaped nucleus,
which can only be seen in stained specimens. Mr. Whitehead
pointed out an important discrepancy which appears between
Saville Kent's description (probably taken from Claparede and
Lachmann) and his own observations. Saville Kent stated that
the posterior horny ring was continuous and denticulate only on
its outer edge. A careful examination of the adherent organ
shows it to consist of an outer circle of cilia, and within this
a circle composed of about eighteen or twenty separate chitinous
teeth, with the points directed obliquely outwards. Vejdovsky,
in 1881, published a detailed account of the species, and stated
that he had found T. Steinii on Planaria gonocephala. As far as
can be seen, the host suffers no inconvenience from the trichodina,
and there is no evidence of parasitism ; consequently the non-
committal term " epizoic " is more satisfactory than " parasitic "
in this case.
A discussion followed, during which Mr. Rousselet said he
remembered, many years ago, finding a T. Steinii on a rotifer.
In reply to a question by Mr. Scourfield about the formation
of chitinous teeth, the chairman stated that some stalked,
non -contractile forms of Vorticella fasten themselves down by
means of a kind of glue exuded by the cilia, which hardens.
Probably these teeth are an adaptation of similar development.
546 PROCEEDINGS OF THE
This interesting contribution was illustrated by a series of
drawings on the blackboard.
Mr. J. Burton read a communication from Mr. E. M. Nelson
on " Palaeozoic Fungi." His object in bringing this subject
forward was to indicate to the members the extreme interest
contained in the study of the flora of palaeozoic days, and in the
hope that some may take up this fascinating branch of science.
Many microscopists are aware of a disease called " diatom-fever " ;
but Mr. Nelson can state that " palaeo-botany fever " produced
a much higher temperature, and he hoped it would prove very
contagious amongst the members. Every one is aware that
botanical fossils have been studied for many years ; but it is
only during the last twenty or thirty years that material suitable
for microscopical examination has been available. The so-called
fossils from coal-mines in museums are not really fossils, but
casts, the plants having become carbonised, and their cellular
structure can no longer be seen. A piece of coal under micro-
scopic examination would reveal no structural cell-work, for that
has been changed long ago. In recent years some true fossil
plants have been found so perfect that sections show the delicate
cell structure almost as clearly as freshly cut and stained sections
of present-day specimens. As an example of the knowledge
obtained by the direct application of the microscope in such
cases, Mr. Nelson takes the fact that coal was formerly con-
sidered to be chiefly formed from ferns, whereas now it is known
that ferns were by no means plentiful in those days, and that the
bulk of coal was formed by other forms of plants. These other
plants had fernlike vegetative characters, leaves, etc., but their
method of reproduction differed entirely from that of ferns. He
instanced how perfectly the vegetable tissues are preserved by a
slide in his collection containing a section of a small seed, with
the pollen grains in the pollen chamber, just previous to fertilisa-
tion, although 50,000,000 years must have elapsed since they
entered. The tracheides and the bordered pits in the cells are
also well preserved. He recommends those wishing to take up
this subject to read Dr. D. H. Scott's charming book, Studies
in Fossil Botany (2 vols., Black), or Ancient Plants, by Miss
Stopes, D.Sc. (Blackie). With reference to a slide exhibited,
a section of a leaf from Lepidodendron Harcourtii — one of the
best known fossil stems, upon which was to be observed a brown
QUEKETT MICROSCOPICAL CLUB. 547
oval ball, and quite a common object in many of these sections
— a power of 200 showed that it is formed in part by little rods,
somewhat interlaced, not unlike the house of the caddis-worm.
They are found singly, but more often in groups, especially
in those parts of leaves where the cellular tissue has been dis-
integrated. Mr. Nelson considers that they are correlated with
this disintegration, and possibly are some sort of fungus spores
(gonidia). It is needless to say that no mycelium has been
observed, so that it is not possible to tell whether the invasion
of the fungus took place while the leaf was living on the tree or
after it had fallen.
The reading of this paper caused considerable discussion.
Prof. Minchin said he remembered Prof. Oliver stating that he
had found cells in coal showing a nucleus.
Mr. N. E. Brown then stated that the brown balls shown on
the slide were certainly not fungus spores, but were more likely
to be of animal origin. Mr. J. Wilson concurred.
Mr. R. Paulson, F.L.S., pointed out that if they were gonidia
they should be on the surface of the leaf. He was interested in
the subject, as he had been trying to find out how far back
lichens are to be found, and had never found traces of even the
lower forms as fossils.
Mr. J. Grundy referred to an address given to the Club by
Prof. W. C. Williamson (Professor of Botany, Owens College,
Manchester) on " The Mineralisation of the Minute Tissues
of Animals and Plants" (Joum. Q. M. C, Ser. 2, Vol. V. p. 186),
which holds very material information for all inclined to learn
more of the subject as to what a fossil is and how formed.
Amongst other exhibits, Mr. G. K. Dunstall, F.R.M.S., showed
a living specimen of the rotifer Callidina bilfingeri, which has
only been seen twice previously in England.
At the 504th Ordinary Meeting of the Club, held on January
26th, 1915, the President, Prof. Arthur Dendy, D.Sc, F.R.S., in
the chair, the minutes of the meeting held on December 22nd,
1914, were read and confirmed.
Messrs. David Griffiths, J. Grant Andrews and Arthur Boltz
were balloted for and duly elected members of the Club.
The list of donations to the Club was read, and the thanks of
the members voted to the donors.
548 PROCEEDINGS OF THE
The Hon. Secretary said that as the next meeting would
be their Annual Meeting, at which the officers and members
to fill vacancies on the committee would have to be elected,
nominations must be made on this occasion. The list of officers
nominated by the committee was then read, and names for the
committee were proposed and seconded by the members An
auditor, on behalf of members, was elected.
At the request of the chairman, Vice-President Prof. E. A.
Minchin, M.A., F.R.S., read a paper giving "Some Details in
the Anatomy of the Rat Flea, Geratophyllus fasciatus"
The paper was illustrated by lantern diagrams projected on to
the screen. A number of micro-preparations made by Prof.
Minchin, illustrating the various points of structure described,
were exhibited under microscopes. These Prof.. Minchin kindly
presented to the Club
The President said he was sure they had all been delighted
with Prof. Minchin's description of the minute anatomy of the
rat flea. The main object of the researches was to trace the
development of the trypanosome found in the rat flea ; but they
had had a full account of the flea, as a type of a class of insects
which exhibited a high development of organisation. He asked
the members to pass a very hearty vote of thanks to Prof.
Minchin for the treat he had given them, for the trouble he had
taken in bringing to the meeting so many specimens, and for his
kindness in presenting the very beautiful preparations to the
Club's Cabinet. This was assented to by acclamation.
At the 505th Ordinary (which was also the 49th Annual)
Meeting of the Club, held on February 23rd, the President,
Prof. Arthur Dendy, M.A., F.R.S., in the chair, the minutes
of the meeting held on January 26th were read and confirmed.
Messrs. Mark T. Denne, Charles H. A. Brooke, W. Powell
Sollis and R. E. Handford were balloted for and duly elected
members of the Club.
The list of donations to the Club was read, and the thanks
of the members voted to the donors.
The President informed those present that news of the
death of Mr. F. W. Millett, F.R.M.S., had been received. He
was one of the oldest members, having joined the Club at
QUEKETT MICROSCOPICAL CLUB. 549
its foundation in July 1865. He was eight}7-t\vo at the time
of his death on February 8th, and had not been able to attend
the meetings for a number of years. He was an authority on
the Foraminifera.
The President asked Mr. Scourfield and Mr. Hilton to act as
scrutineers of the ballot for officers and council of the Club for
the ensuing year. He wished to mention that any member
could erase the name of any of the officers, if he thought proper,
and substitute the name of any other person in the space pro-
vided on the ballot paper for that purpose. Five members of
committee would have to be elected in place of four who retired
by rotation and of Mr. Heron-Allen, who had resigned. Six
members were nominated at the last meeting, but since then
Mr. Lionel C. Bennett had withdrawn his name, so that the
number remaining would fill the vacancies.
The Hon. Secretary read the committee's report, which detailed
a satisfactory year's work, though the war had somewhat inter-
fered with the personnel of the Club.
The Hon. Treasurer read the balance sheet, which disclosed
a thoroughly sound financial condition.
The adoption of the report and balance sheet having been
moved and seconded, was put to the meeting by the President,
and unanimously carried.
The President then asked Prof. Minchin to take the chair,
and proceeded to give his annual address. The title was " The
Biological Conception of Individuality."
At the conclusion Prof. Minchin said they had just listened
to a most interesting and instructive address — one which they
would be glad to think over and to read in their Journal, if
Prof. Dendy would kindly allow them to print it. He moved
that " The hearty thanks of the meeting be given to the Presi-
dent for his address, and that he be asked to allow it to be
printed in the Journal."
The motion was carried by acclamation.
Prof. Dendy, in reply, thanked those present for the attention
paid to his remarks, and said he should be extremely pleased to
place the address at their disposal for publication.
A vote of thanks to the scrutineers and auditors was proposed
and carried.
A vote of thanks to the officers and committee was proposed
550 PROCEEDINGS OF THE QUEKETT MICROSCOPICAL CLUB.
by Mr. Capell, F.R.M.S. He did not think this should be done
as a mere matter of form. The members came to the meetings
and found things went along smoothly, and the work was done
for them efficiently and with willingness and cheerfulness, and
they all gained by the efforts of those who carried it on.
The proposal was seconded by Mr. Gammon, and carried.
The Hon. Treasurer (Mr. F. J. Perks) acknowledged the vote.
He said there was a considerable amount of work done by the
officers apart from that which was apparent at the meetings.
He thanked them for their kind expressions, and could promise
they would in the future, as in the past, do their best for the
prosperity of the Club.
The scrutineers having handed in their report, the following
gentlemen were declared duly elected as —
President
Four Vice-Presidents
Hon. Treasurer
Secretary
A ssistant Secretary
Foi*eign Secretary .
Reporter ....
Librarian . . .
Curator ....
Editor ....
Members of
Committee.
Prof. Arthur Dendy, D.Sc, F.R.S.
[G. F. Rousselet, F.R.M.S.
E. J. Spitta, L.R.C.P., M.R.C.S.,
F.R.M.S.
D. J. Scourfield, F.Z.S., F.R.M.S.
IProf. E. A. Minchin, M.A., F.R.S
Frederick j. Perks.
James Burton.
F. E. Robotham.
C. F. Rousselet, F.R.M.S.
R. T. Lewis, F.R.M.S.
S. C. Akehurst, F.R.M.S.
C. J. Sidwell, F.R.M.S.
A. W. Sheppard, F.Z.S., F.R.M.S.
fj. M. Offord, F.R.M.S.
Charles S. Todd.
N. E. Brown, A.L.S.
Ed. E. Banham.
IC H. Bestow, F.R.M.S.
551
FORTY-NINTH ANNUAL REPORT.
Your Committee in presenting their Report for the year ending
December 1914 will scarcely need to remind members that for
almost half the time covered by it, namely the last five months,
conditions have been of an altogether abnormal and unpropitious
character. Taking this into account, it is satisfactory to find
that the number of members elected has been forty-one ; this is
slightly above the average of the previous six years. The resig-
nations have been twenty-five, which is more than usual, and
was largely due to enlistment and other circumstances connected
with the war. The deaths have been nine, again somewhat more
than the average, removing some of our older and more noted
members; leaving the present membership 447.
Dr. Arthur Mead Edwards of New Jersey, U.S.A., the oldest
honorary member, elected in January 1868, died in September.
Ln November we had to regret the loss of Dr. M. C. Cooke. He
has been not inappropriately called the " Father of the Club " ;
he was not only one of its founders, but his writings and general
work must have done an incalculable amount to disseminate a
popular interest in, and knowledge of, microscopy. Although he
was in his ninetieth year at the time of his death he had shortly
before, on the celebration of our five hundredth meeting, been
able to write, with his own hand, a letter expressing his pleasure
at the prosperity of the Club, and his wishes for its continuance.
An obituary notice appeared in the November number of the
Journal.
Among the losses sustained owing to the war, it should be
recorded that Mr. Pledge, Assistant Secretary for nine years, has
been compelled to resign his office in consequence of having to
place himself at the disposal of the military authorities ; and we,
therefore, no longer have the advantage of his very excellent
reports of our meetings in the English Mechanic and elsewhere,
for which it has been the pleasing duty of the Committee so often
to express their thanks to him. The Club is to be congratulated
on the fact that Mr. Robotham kindly consented to fill the vacant
552 FORTY-NINTH ANNUAL REPORT.
position, and for some months has earned the thanks of all by
his efficiency in performing the duties connected with it.
The number present at both the Ordinary and Gossip Meetings
has been good, though for the latter part of the time it has been
lessened somewhat by the absence of previously regular attendants
owing to engagements in various capacities in the army, as well
as by the general unrest brought about by the war. On the
Gossip nights there has been no less enthusiasm and good work
done than previously ; but the Committee wish, while thanking
those who have done so much to make these meetings a success,
to press upon the attention of all, the desirability of their making
an effort to bring a microscope and some object for exhibition,
and thus add their endeavours for the well-being of the whole.
The papers and notes read were as follows :
Communications during 1914.
January 27th. — Some Observations on Sub-stage Illumination,
by S. C. Akehurst.
January 27th. — On an Attempt to Resolve Pinnularia nobilis,
by T. A. O'Donohoe.
February 2ith. — President's Address : Organisms and Origins,
by Prof. Arthur Dendy, D.Sc., F.R.S.
March 2kth. — Some Notes on the Structure of Diatoms, by N. E.
Brown, A.L.S.
March 2kth. — On a New Oil-Immersion Objective and On a New
Method of Illumination, by E. M. Nelson, F.R.M.S.
April 2&th. — On a New Low-power Condenser, by E. M. Nelson,
F.R.M.S.
April 2&th. — On the Fertilisation of Vinca minor, by N. E.
Brown, A.L.S.
May 26th. — Notes on the Cultivation of Badhamia utricular is,
by A. E. Hilton.
May 26th.— On Binocular Microscopes, by E. M. Nelson, F.R.M.S.
June 23rd. — Notes on Fossils from the Coal Measures, by W. E.
Watson Baker.
June 23rd. — Notes on the History of tjie Club, in Celebration of
the 500th Ordinary Meeting, by Dr. E. J. Spitta.
October 27th. — Report of the Havre Meeting of the British
Association, by C. F. Rousselet, F.R.M.S., the Club's
delegate.
FORTY-NINTH ANNUAL REPORT. 553
October 21th. — On the Minimum Visible, by A. A. C. Eliot Merlin.
October 27th. — Remarks on two Species of African Vol vox, by
C. F. Rousselet, F.R.M.S.
November 24th. — A New Copepod found in Water in the Hollows
on Tree Trunks in Epping Forest, by D. J. Scourfield, F.Z.S.
December 22nd. — On an Epizoic Infusorian — Trichodina, found
on the Planarian Mesostoma tetragonum, by Mr. White-
head, B.Sc.
December 22nd. — Palaeozoic Fund, bv E. M. Nelson, F.R.M.S.
Your Committee thanks the authors of these valuable com-
munications on behalf of the members. It may be observed that
short notes are more frequent than usual, and it is desired to
express the appreciation in which this class of communication
is held ; those who are not able to undertake a lengthy and
scientific paper may still be able to add their quota to the work of
the Club by giving short accounts of their finds, and of the
methods and experiences of their investigations.
Several new and useful pieces of apparatus — often the inven-
tion of our own members — have been exhibited and described.
Notice of these will be found in the reports of the meetings
in the Journal.
The veteran microscopist, Mr. E. M. Nelson, as in former years,
has laid the Club under an obligation by his numerous and inter-
esting communications. In May he gave a paper on " Binocular
Microscopes," very fully treating the subject of the new high-
power binoculars. At the same meeting Messrs. Beck and
Messrs. Leitz exhibited samples of this class of instrument, thus
giving an opportunity of judging their capabilities, and greatly
adding to the interest of the proceedings. In November Mr.
Scourfield read a paper describing a new species of Copepod he
had found in Epping Forest. The discovery by Mr. Rousselet of
the sexual forms of two species of African volvox, among speci-
mens he had received from Dr. Jakubski of Lemberg, is note-
worthy. The account of the experiences of Mr. Rousselet as
delegate to the Havre meeting of the Corresponding Societies of
the British Association on the eve of the outbreak of war is given
in the Journal.
In February a Conversazione was held at King's College : this
was much appreciated by members and their friends. It was the
Journ. Q. M. C, Series II.— No. 76. 38
554 FORTY-NINTH ANNUAL REPORT.
first that the Club had held for seventeen years, and the hope
was freely expressed that so long a time would not be allowed to
elapse before another occurred.
The meeting on June 23rd was the five hundredth Ordinary
Meeting. In the absence of the President — who had just left
for Australia as the President of the Zoological section of the
British Association — the chair was taken by Dr. S pitta, who,
in celebration of the occasion, gave the meeting a more social
character than usual, quite in accordance with the older tra-
ditions of the Club.
The Librarian reports that, notwithstanding some inconveni-
ence being felt owing to the restricted space at his disposal, the
average number of books borrowed in previous years has been
maintained. The Library sub-committee has met regularly on
the first and third Tuesdays in the month, and members will be
glad to hear that, after considerable but unavoidable delay, the
Catalogue of Books is in the hands of the printers. This, com-
bined with the appointment of Mr. Todd as Assistant Librarian,
will render the work of the department more expeditious, and it
is hoped that advantage will be taken of the increased facilities.
The best thanks of the Club are due to Mr. Todd, to Mr. Shep-
pard and to Mr. Bennett, for the interest and energy they have
exercised in carrying out the by no means light task of re-
organising the Library.
List of Books Purchased and Presented since October 29th,
1914, to January 1915.
Memoirs of Indian Museum. Vol. III. 4. Oriental Passalidae
(Coleoptera). F. H. Graveley, M.Sc.
Presented by W. Harold S. Cheavin.
Water Beetle (JJytiscus marginalis), Common Gnat (Culex
pipiens).
Reports on Hydroida collected in the Great Australian
Bight and other Localities. Parts II. and III. W. M.
Bale, F.R.M.S.
Purchased.
►Some Minute Animal Parasites. Fantham and Porter.
FORTY-NINTH ANNUAL REPORT. 555
Missouri Botanic Garden.
Philippine Journal of Science.
Bergen Museum.
United States National Herbarium.
Royal Society. B Series.
Natural History Society of Glasgow.
Zoologisch-botanischen Gessellschaft Wien. LXIV. Parts 1-4.
1914.
United States National Museum.
Nuova Notarisia.
Liverpool Microscopical Society.
Royal Dublin Society.
University of California.
Illinois State Laboratory of Natural History.
Societe Roy ale de Botanique de Belgique. Tome LIL Series II.
March 1914.
Brighton and Hove Natural History and Philosophical Society.
Edinburgh Royal Botanic Garden
Northumberland and Durham Natural History Society.
Torquay Natural History Society.
Photographic Journal.
During the year ending December 1914 the Library has
received the following publications :
Quarterly Journal of Microscopical Science.
Victorian Naturalist.
Mikrokosmos. Up to Part 5. 1914-1915.
Royal Microscopical Society.
British Association Report.
Royal Institution of Great Britain, Proceedings of.
Geologists Association.
Manchester Literary and Philosophical Society.
Hertfordshire Natural History Society.
Botanical Society of Edinburgh.
Tijdschrift.
Nyt Magazine.
Manchester Microscopical Society.
Birmingham and Midland Institute.
Glasgow Naturalists' Society.
556 FORTY-NINTH ANNUAL REPORT.
Croydon Natural History Society.
Indian Museum., Calcutta.
Royal Society of N.S.W.
American Microscojncal Society.
Smithsonian Institution.
Academy of Natural Science, Philadelphia.
Missouri Botanic Garden.
Philippine Journal of Science.
Bergen Museum.
During the year eleven excursions were held, at which the
average attendance was 23, against 20-8 for last year. Notwith-
standing the inclement weather on some of the dates, the average
attendance for the year is a record. An excursion had been
arranged for August 8 to Hampton Court, but owing to the
unfavourable weather and the excitement caused by the war, it
was abandoned. Arrangements had also been made for an
excursion to the East London Water Works, but owing to the
war, the authorities cancelled the permission. An excursion
instead was made to various ponds in Epping Forest, which was
very successful. There were no new species to record, but
Lemna minor was found abundantly in flower in one of the ponds
in Trent Park. The thanks of the Committee are due to His
Grace the Duke of Northumberland and to Sir Philip Sassoon
for the permission to visit their private grounds.
The Curator reports that all through the year there has been
a steady demand for the slides and instruments under his care,
and 111 preparations have been added to the Cabinets. The
principal addition has been the purchase of 47 fine slides of
selected Diatoms mounted in styrax, thus bringing up the Club's
collections of Diatomaceae to 1,550 preparations. For some
time past Mr. Rousselet has been engaged in the onerous task of
overhauling, and in many cases remounting, the type-collection
of Rotifera he presented to the Club some years since, to
which he has recently made a further donation of 24 slides,
thus increasing the total to over 260 species. The cordial
thanks of the Club are due to Mr. Rousselet for his labours, and
the Club is to be congratulated on possessing what is believed to
be the most complete type- collection of Rotifera in the worldj
with the exception of Mr. Rousselet's private collection. Up to
FORTY-NINTH ANNUAL REPORT. 557
the present these slides have only been available for reference at
the rooms ; but after careful consideration the Committee has
decided to lend out the preparations, under certain conditions, to
members specially interested in the group. The Committee has
felt it necessary to make some restriction, owing to the delicate
nature of the slides, and the difficulty of replacing many of the
rarer species in the event of accidental damage, as any such loss
would considerably detract from the value of the preparations as
a type-collection. The demand for slides is generally from the
newer members, and the Committee regrets that greater use is
not made of the Cabinets by the older members and those who
are specialising, as the Cabinets contain many preparations which
could not fail to be of use and interest to them. The Curator
will be pleased to render any assistance and information in this
respect.
The Committee again begs to tender its best thanks to
Mr. Bestow for kind assistance rendered to the Curator in the
issue of slides.
Thanks are due to the Editors of the English Mechanic and of
Knowledge for their kindness in publishing reports of the
Meetings.
Your Committee desires to thank the various Officers for the
unabated energy they have displayed in carrying on the work of
the Club, work which they are conscious not seldom entails a
considerable amount of self-denial, but the reward for which is
the continued prosperity and usefulness of the Club, founded now
nearly half a century ago.
558
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559
OBITUARY NOTICE.
FORTESCUE WILLIAM MILLETT, F.G.S., F.R.M.S.
Born November Sth, 1833; died February Sth, 1915.
It is with feelings of great regret we have to record the death,
in his eighty-second year, of Mr. F. W. Millett, which took place
on February Sth at his residence in Brixham, Devon.
Mr. Millett was a native of Marazion, in Cornwall, and when
about twenty years of age came to reside in London. From
an early age he was of a studious nature, and his connection
with the Quekett Microscopical Club — he joined at its foundation
in July 1865 — fostered an early taste for microscopical work.
He was elected F.R.M.S. in 1880, and in 1883 left London
to reside in Cornwall. From about that date the study of the
Foraminifera became his principal life-work.
His first paper, "The Foraminifera of Gal way," written in
collaboration with F. P. Balkwill, was published in the Journal of
Microscopy and Natural Science in 1884. It was a paper of
considerable zoological importance, but the lithographed plates
were very poor, and it is not surprising that Millett later revised
the paper and issued it in 1908 as a private reprint with half-
tone reproductions of the original excellent drawings. Between
1885 and 1902 Millett published a series of short papers on the
Foraminifera of the Pliocene Beds of St. Erth, Cornwall, which
obtained for their author recognition from the Royal Geological
Society of Cornwall in the form of the William Bolitho gold
medal. But his future reputation will rest principally and
securely on his " Report on the Recent Foraminifera of the Malay
Archipelago," which appeared in the Journal of the Royal
Microscopical Society at intervals between 1898-1904. This
monograph, illustrated profusely by the author, dealt with a new
zoological area and contained descriptions of many new and
interesting forms. But its chief value to the student lies in the
careful research work embodied in the author's bibliographical
references to the numerous species which he recorded from the
material examined. This was unquestionably Millett's strongest
560 OBITUARY NOTICE.
point, for he had devoted a lifetime to the collation and
assimilation of the work of his predecessors, both British and
foreign, and no man had a wider knowledge of the subject, or
was more ready to place it at the disposal of fellow-workers.
With the death of F. W. Millett parses almost the last
survivor of the famous band of systematists who have made
British research into the Foraminifera famous throughout the
world. Started by Williamson and continued by the famous
collaborators W. K. Parker, Rupert Jones and H. B. Brady,
and by the equally distinguished W. B. Carpenter, their
systematic work has reduced to a more or less exact if artificial
science the chaos in which the group had previously existed.
Millett assisted Brady in the preparation of the great
"Challenger" report (1884), to what extent it is impossible to
say, but probably he was largely responsible for the elaborate
synonymies which render that report so valuable. He also
collaborated in the Monograph of the Foraminifera of the Crag,
published by the Palaeontographical Society, and here his
systematic work is more easily traced. If his total output of
publications is small as compared with other workers in the
group, it was largely due to the painstaking care which he
lavished on his work. Few rhizopodists will be less revised by
the publications of their successors than F. W. Millett, and after
all that is the real test of scientific work.
561
AN ADDITION TO THE OBJECTIVE.
By M. A. Aixslie, R.X., B.A., F.R.A.S.
{Read April 21th, 1915.)
Figs. 1 and 2.
Probably there are few microscopists who are in the habit of
using high-power dry objectives who would not agree that the
Correct adjustment of the tube-length to suit the thickness of
the cover-glass is with such lenses of great importance if good
definition is to be obtained. Definition of a sort may, it is true,
be got with incorrect tube-length ; but only by unduly closing-
down the iris diaphragm and thus reducing the illuminating
cone, or otherwise interfering with the uniformly illuminated back
lens which is the basis and starting-point of all correct microscopic
vision. In the present paper I am not considering inferior
definition got in this way ; I am only considering the question
of obtaining really sharp definition, with a cone of illumination
which utilises at least two-thirds of the aperture of the objective ;
and this is what I mean when I speak of " good ' ' definition ;
and such is only to be obtained by careful adjustment of the
tube-length to suit the thickness of the cover-glass.
With objectives fitted with correction collars this paper has
not much to do ; the correction collar to a large extent obviates
the change of tube-length without interfering much with the
magnifying power, and is useful in other ways, as for example
in focusing through the various planes of a thick object ; but
unfortunately it seems to be going out of use, except in the dry
apochromats and in water-immersions ; and as 99 out of 100 of
the high-power dry objectives met with at the present time
are without this appliance, I shall not take it into further con-
sideration, but confine my attention to the objective as com-
monly used.
If we open a treatise on Microscopy, we are pretty sure to
find the question of cover-glass and tube-length alluded to more
or less (usually less) fully. The reader is told that for a thick
Jourx. Q. M. C, Series II.— No. 77.
562 M. A. AINSLIE ON AX ADDITION TO THE OBJECTIVE.
cover-glass the tube is to be shortened, and that it is to be
lengthened for a thin ; and the importance of the matter is
impressed on the reader, even to the extent of saying that " the
correction of the objective and the tube-length ought to vary
with every object" (Dallinger), a statement which would appear
to require some modification in the case of oil -immersion objec-
tives.
Little, however, is usually said as to how the correct tube-
length is to be recognised when obtained, and nothing as to
how much we may expect to have to move the draw-tube. On
this latter point I hope to give some data which may prove
useful.
One of the first things to strike any one who tries to examine
a few mounted specimens, with, say an l/8th, is that the range
of draw-tube of the modern stand is often insufficient to allow
for more than a very slight variation in the thickness of the
cover-glass ; and this is more particularly the case with stands
of Continental make, in which the available range is often not
more than 50 mm. ; and to give some idea of what a hindrance
to observation this may prove, I may say that with an English
•stand (by Watson) having the good range of tube-length of 92 mm. ,
-and using a Leitz No. 7 (which is a 1/8 tli of N.A. 0*85), I have
found it impossible to examine some of the beautiful slides of
Diatomaceae in the Club Cabinet, in some cases because the
cover-glasses were too thin, and in other cases because they
were too thick. With the limited range of the Continental
draw-tube one would, of course, be still worse off.
Another point on which the text-books are silent, but which
soon becomes evident to any one who has occasion to use objec-
tives of different powers, is that the change of tube-length
necessary to correct for a given variation in the thickness of
the cover-glass is not always the same ; it varies enormously
with the power of the objective, and also, to some extent, with
the formula on which the objective is constructed. At one end
of the scale we have such objectives as the half-inch " Holos '
of Watson & Son, N.A. 0*65, which requires a change in the
tube-length of about 1*2 mm. only to compensate for a variation
of 0*01 mm. in the thickness of the cover-glass ; and the Zeiss
12 mm. Apochromat, of the same N.A., which requires a change
of about 2 mm. under the same conditions.
M. A. AIXSLIE ON AX ADDITION TO THE OBJECTIVE 563
These objectives have, in fact, the extremely useful property
of working through almost any cover-glass ; even through a
thin slip, if the tube-length be closed down sufficiently, which
in the case of these objectives is almost always possible.
As we increase the power of our objectives, the alteration
required in the tube-length increases rapidly ; to give only a
few instances, the figures are roughly as follow for certain
typical objectives :
Watson 6 mm. Holos, N.A. 0'84 . . .3*4
Leitz No. 5 (l/5th-in.) 7*5
Watson l/6th-in., N.A. 0'74 9D
Zeiss " G " water-immersion .... 9'5
Zeiss 4-mm. Apo. (without using correction collar) 13'0
Leitz No. 6 (l/6th-in.) 14-0
Leitz No. 7 (l/8th-in.) 20'0
So that a typical l/8th-in. is ten times as sensitive in this respect
as the Zeiss 12-mm., and seventeen times as sensitive as the
Watson 1/2-in. " Holos."
In passing, I must say that this seems to me to be a strong-
point in favour of the employment of objectives of moderate
power, as long as they are of sufficient excellence to stand the
high eye-piecing necessary to give the desired magnification.
The difficulty of using such a lens as the Leitz No. 7 with a range
of only 50 mm. in the draw-tube will now be fairly obvious.
It might be thought that a good deal of this difference between
objectives of different powers is due to the N.A. of the higher
powers being, as a rule, greater than that of the lower ; but the
above figures are practically unaltered when the N.A. is reduced to
about 0'6 in each case, though of course the effect of incorrect
tube-length on the definition is not so marked as with the full
aperture.
Although I am confining my attention to objectives with
N.A. not less than about 0'65, it must not be thought that those
of lower N.A. are altogether insensitive to correct tube-length ;
a 25-mm. objective of N.A. 0"3, for example, will not work
really well at any but its computed tube-length, although such
objectives are not very sensitive to alterations in the thickness
of the cover-glass.
564 M. A. AINSLIE ON AN ADDITION TO THE OBJECTIVE.
I now come to the device which I am bringing to your notice
for overcoming the difficulty caused by insufficient range of
draw-tube.
Many years ago the late Dr. Van Heurck used what he
called a " transformer," for the purpose of enabling short-
tube objectives to work on the long tube, and vice versa. I
do not know that he used it for any other purpose, or with
a view of compensating for insufficient range in the draw-
tube.
He applied, behind the objective, a lens of small power, either
convex or concave, according to the effect desired, and stated
that in this way he was able to use even a 2-mm. Apochromat,
corrected for the short tube, on the long tube, without any
appreciable loss of definition. The lenses he used were, I believe,
achromatic.
But it has occurred to me that the utility of this device is of
far wider range than this. In the course of a series of experi-
ments with a large number of dry objectives of various (high)
powers, I have found that it is possible to increase very greatly
the range of thickness of cover-glass through which the objective
will give good definition ; and I hope, later on, to show another
use for this additional lens, which has not, so far as I am aware,
been described before.
If a convex or concave lens of low power be introduced im-
mediately behind the objective, it has the effect of altering the
degree of convergence of the rays of light projected by the back
lens of the objective, and thus of altering the position in which
the image is formed. Conversely, if the objective requires, to
give good definition, that the image should be formed in a plane
either within, or beyond, the available limits of the tube, it is
perfectly possible, in the great majority of cases, to find a lens
of such a power that its introduction above the objective will
bring the image within the limits of the tube.
Suppose, for example, that we have a cover-glass so thick that
the objective will only form a perfect image of the object at a
point too close to the back lens for the tube to be sufficiently
shortened ; it is true that we can, by using the focusing adjust-
ments, bring the image to the top of the tube, but then we do
not get a perfect image ; that is to say, not perfect in the sense
M. A. AINSLIE OX AX ADDITIOX TO THE OBJECTIVE. 565
that it is the best that the objective will do. A perfect image
is only formed, for any given thickness of the cover-glass, at one
particular distance from the back lens, and at no other.
To take a numerical example, which will probably help to make
this point clearer, suppose we have a cover-glass so thick that
the correct tube-length is no more than 100 mm. It is obvious
that the tube cannot be closed down as much as this, except on
a stand of very exceptional construction.
To treat the objective for the moment as an animate thing,
we can as it were leave it under the impression that it is forming
the image at the point where it can do so best, i.e. at 100 mm.
from the bottom of the tube. If we now introduce behind the
back lens a concave lens of low power, we decrease the conver-
gence of the beam projected by the objective. This in no way
affects the working of the objective, since the action of this new
lens does not commence until the objective has finished its work ;
but if the power of the additional lens is suitably chosen, we
can so alter the degree of convergence of the beam of light as
to make it come to a focus, say, at a distance of 170 mm. from
the back lens — that is to say, well within the limits of an ordinary
draw-tube. We have, in fact, altered the tube-length for which
the objective is corrected. If the thickness of the cover-glass
be still further increased, we have only to introduce a lens of
shorter focus, and therefore of greater power, to bring the image
within the limits of the draw-tube as before ; and it will readily
be seen that this gives us the power, within somewhat wide
limits, of obtaining good definition through a thickness of cover-
glass which would in ordinary conditions be a complete bar to
anything like good definition.
Conversely, if the cover-glass is inordinately thin, the distance
at which the perfect image will be formed may be considerably
beyond any length that the draw-tube will reach ; but the
introduction of a convex lens of suitable power will increase the
convergence of the beam of light, and so bring the image to a
distance at which the draw-tube can deal with it.
Figs. I. and II. are intended to illustrate the action of the
additional lens ; in each figure,
P is the object ;
O is the objective, shown diagrammatically as a single lens
C is the cover-glass (thick in I., thin in II.) ;
566 M. A. AINSLIE ON AN ADDITION TO THE OBJECTIVE.
A is the additional lens (concave in I. for a thick cover, convex
in II. for a thin) ;
U and L are the upper and lower limits, respectively, of the
draw-tube ; the image must be formed between these limits to
be capable of being focused by the eyepiece ;
Vis the point at which the objective must produce the image,
if it is to be the best possible ; it will be seen that in each case V
lies outside the limits of the draw- tube, so that the best possible
image could not be focused by the eyepiece ;
T is the point, well within the limits of the draw-tube, to which
the image V is transferred by the additional lens.
The actual path of the rays is in each figure shown by dark lines ;
the broken lines show the paths that would be followed in the
absence of the additional lens.
It would, no doubt, be possible, by the use of the focusing
adjustments of the microscope, to bring an image of a sort, in
either case, within the limits U, L ; but it would not be the best-
possible, indeed in the majority of cases it would be very inferior,
owing to the tube-length being incorrect ; the function of the
additional lens is to allow the objective to work at the proper
tube-length OV, but to bring the " best possible " image, formed
at the proper tube-length, within the available limits of the draw-
tube.
With objectives of not too high power — the ordinary l/6th-
in., for example — there is scarcely any limit to the amount
of correction which can be produced in this way. Take,
for instance, an objective (Watson 4 mm. Apochromat,
N.A. 0'85) corrected in the usual way to work through a
cover-glass 0'18 mm. in thickness, working on an uncovered
object, and it will be seen that the definition is good. In
this case a convex lens of + 4 diopters is placed behind the
objective. WTith a dry l/8th-in., however, or with dry ob-
jectives of still higher power, it is not possible to go quite
so far as this, though the results to be obtained are by no
means bad.
I am showing the objective working on an uncovered object
with a view of demonstrating the amount of correction that
may be obtained in this way ; at the same time I ought to
say that this is not the best way of making an ordinary objective
work on an uncovered object : the best and easiest method is by
u
u
4^^^A
O
c
II
567
568 M. A. AINSLIE ON AN ADDITION TO THE OBJECTIVE.
oiling to the front lens a small piece of cover-glass of the thickness
for which the objective is corrected, which will enable it to work
exactly as it was intended to work. As far as the aberrations
produced are concerned, it is a matter of indifference whether
we place the cover-glass next to the object or next to the
front lens ; and the advantage of oiling it to the front lens
is that there are no reflections introduced to dull the image.
If the precise change in tube-length necessary for a given
change in the thickness of the cover-glass were known in the
case of a given objective, there would be no difficulty in calcu-
lating the power of the additional lens required to effect the
correction ; but, as has been seen, objectives vary so enormously
in this respect that it is of little use to give any rules for the
purpose. Each objective ought to be fitted with appropriate
lenses, just as a defective eye has to be fitted with spectacles
Speaking generally, it will be found that with the ordinary
l/6th-in., a pair of lenses, convex and concave, if about 10-in.
focus, or -f- and — 4 diopters, will cover all the ground likely
to be required. With lenses of this power, and a range of tube-
length from 167 to 259 mm., I find that a Watson l/6th-in., of
N.A. 0*74, corrected normally for a tube-length of 200 mm., and
a cover-glass 0*18 mm. thick, will give good definition with any
thickness of cover-glass from zero to 0*35 mm. ; with a concave
lens of 10 diopters, or 4-in. focus, the thickness can be as much
as \ mm. Without the additional lens, the variations of thickness
of cover-glass which can be allowed for with the above range
of draw-tube is from 0*11 to 0'21 mm., so that the introduction
of the lenses of -f- and — 4 diopters has more than trebled
the range of thicknesses through which the objective will work.
This particular objective is rather a favourable example, since
its sensitiveness to cover-glass thickness is less than that of
many objectives of its power ; but with any objective of this
power, and to a somewhat less extent with objectives of higher
power, the advantage of this device is evident. With objectives
of higher powers, the available range of thicknesses is less,
unless the power of the additional lens is raised ; for example,
a Leitz No. 7 cannot be made to work on uncovered objects
in this way unless with a convex lens of at least 10 diopters
power, or 4-in. focus, and even then the result is not nearly
so good as in the case of a l/6th-in. This again illustrates the
M. A. AIXSLIE ON AN ADDITION TO THE OBJECTIVE. 569
advantages possessed by objectives of medium power over those
of very high power.
It will be seen then, I think, that this device places a con-
siderable power of correcting for cover-glasses of abnormal
thickness in the hands of the microscopist, especially with the
miserable 50 mm. range of the Continental draw-tube ; and it
now remains to be seen what the effect of this additional lens is
on the power, N.A., and corrections, spherical and chromatic,
of the objective.
Firstly, as regards the power. If the additional lens could in
practice be fitted in the ;' upper focal plane " of the objective — •
that is to say, in the plane in which a pencil of parallel rays
entering it from below would come to a focus — there would be
no alteration of power. But in most objectives — in all those of
high power, in fact — this upper focal plane is not far behind
the front lens, and therefore inaccessible. So we have to put
up with a certain increase of power in the case of the concave
lens, and a decrease in the case of the convex ; but if the power
of the additional lens does not exceed 4 diopters either way, i.e.
if its focal length is not less than 10 in., the alteration of power
is not serious. It is an advantage to have the additional lens as
near as possible to the back lens of the objective, but if there
is any difficulty in fitting it there, it does very well to place it
on the nosepiece.
The effect on the working distance of the objective is not
serious : the concave lens increases the working distance, and
the convex lens diminishes it ; but since the former is used in
the case of thick cover- glasses, and the latter in the case of
thin, it will be seen that the change is in the right direction, so
that this point need not worry us.
Similarly the effect on the N.A. is not great. The convex
lens somewhat diminishes it, and the concave lens may (it does
not always) slightly increase it ; but the change is not great,
and for most purposes unimportant.
It is of more importance to inquire what effect, if any, the
introduction of the additional lens has on the spherical and chro-
matic corrections. To take the former, it so happens that the
spherical aberration introduced by the additional lens slightly
counteracts its effect in producing the result desired ; a simple
uncorrected lens does not quite produce the full theoretical effect
570 M. A. AINSLIE ON AN ADDITION TO THE OBJECTIVE.
it would have if it were corrected for spherical aberration ; but
in any case the additional lens is small, and of low power, so that
the effect of its spherical aberration is very slight, and only in-
volves a small movement of the draw-tube. Since the final
adjustment of the draw-tube would in any case be performed by
actual inspection of the image, it will be easily realised that the
effect of the spherical aberration of the additional lens is quite
unimportant.
With regard to the chromatic effect, I have only used simple
uncorrected lenses in my experiments. Even with these, the
effect on the colour correction of the objective is extremely
small, except perhaps in the case of an additional lens of
10 diopters.
The only effect that is at all noticeable is that with the convex
lens in use the "compensation' required in the eyepiece, to
do away with the chromatic difference of magnification (present
in all lenses having a single front lens) is somewhat diminished ;
in the case of the concave lens, it is somewhat increased ; but
this effect is only seen if specially looked for, and with ordinary
Huyghenian eyepieces would not be noticed.
There is, however, a curious effect to be seen in some cases,
with objectives which under normal conditions show a certain
blue tint on the margins of black objects ; and many of
the finest achromatic lenses of the present day, noticeably
Watson's Holoscopic, show this effect, which indeed I am informed
betokens a more than usually good spherical correction, and
in consequence more than usually good definition. I have a
Holos 25 mm. objective, of measured N.A. 0'31, corrected for the
250 mm. tube ; this, on black objects, such as the lines on the
Abbe test plate, shows the blue tint I have alluded to. When the
correction of this lens is altered to the short tube by the intro-
duction of a convex lens of 2 diopters (20 in. focus), the blue tint
almost disappears, and the total quantity of outstanding colour
is greatly diminished, so that the additional lens has a sort of
" apochromatising ' effect ; this is probably due to the fact
that the additional lens slightly alters the 'k preferred colour,"
for which the spherical correction of the objective is carried
out ; but to my eyes there is little, if any, loss of definition on
this account, and the 27 compensating eyepiece can still be used
with advantage.
M. A. AIXSLIE ON AN ADDITION TO THE OBJECTIVE. 571
The additional lenses above described are easily fitted behind
the objective if they are mounted in small cells which push
into a ring made to screw to the nosepiece, and having a thread
in front to take the objective. Otherwise they may, as stated
above, be fitted immediately behind the back lens, and almost
in contact with it ; but this is hardly necessary, unless it is
important that the power of the objective should be affected as
little as possible. The lenses I have had made are just over
1-i mm. in diameter, and the outside diameter of their cells is
rather less than 15*5 mm., so that there is ample room for
them to push into the upper side of the ring suggested, leaving
sufficient thickness in the ring for the thread to fit the nose-
piece.
They were beautifully made and fitted for me by Messrs.
H. F. Angus & Co., who supplied me with a series of 11 of these
lenses, varying in power from +10 to — 10 diopters. With
this series almost anything can be done in the way of cover-
glass correction.
I have tried both biconvex and biconcave, and plano-convex
and plano-concave lenses, the latter with the plane side both
upwards and downwards, without being able to see any difference
in the performance ; biconvex and biconcave lenses are easier
to obtain, and I should recommend them to any one thinking
of trying this device.
So far we have been dealing with the use of an additional lens
with dry objectives ; but I now come to a use for this device
which has not, as far as I know, been suggested before. I refer
to the conversion of an oil-immersion objective into a water-
immersion.
Some time ago I found that with certain oil-immersion objec-
tives it was possible to get good definition with glycerine as
the immersion fluid if the tube length was increased by 60 mm.
or so. Was it possible to use these objectives as water-immer-
sions ?
The substitution, in the case of an oil-immersion objective,
of a medium of smaller refractive index for the oil has an effect
on the corrections of the objective precisely similar in kind to
the reduction in the thickness of the cover-glass in the case of
a dry objective ; in each case the effect is really due to the
572 M. A. AINSLIE OX AN ADDITION TO THE OBJECTIVE.
reduction of the average refractive index in the space between
the front lens and the object, except that in the case of the sub-
stitution of water for oil the effect is greatly increased.
It was quite obvious, the moment I tried the experiment, that
mere increase of tube-length would not by itself make an oil-
immersion l/12th work as a water-immersion, on any cover-
glass that was likely to be met with ; but as soon as the idea
of the additional lens, as described above, occurred to me, it
immediately suggested itself as a way out of the difficulty. But.
as a rule, in the case of the conversion of an oil-immersion into
a water-immersion, the power of the additional lens has to be
much greater than is required with a dry lens, to correct for an
unusually thin cover-glass. In fact, it is generally necessary
to use a lens of such great power that the pencil of rays emerging
from the back lens of the objective is actually divergent instead
of convergent ; so that the correct position for the image has
actually " passed infinity " and the tube-length is negative, or,
in other words, the best image that can be formed by the ob-
jective is a "virtual image" several inches below the object!
It is hardly necessary to say that this means upsetting all the
corrections of the objective, and at first sight it does not look-
very promising.
But on trial it was found that it was only the extreme margin
of the objective that was adversely affected. With an illuminat-
ing cone of not more than about 0'75 or 0'8 N.A., the definition
becomes quite satisfactory, and it appears that the central
portion of the objective is not to any great extent affected by
the violence done to it.
Here again, as with dry objectives, an objective of moderate
power is much more amenable to the action of the additional
lens than one of very high power. The Zeiss l/7th-in., of N.A.
about 0'93, only requires a convex lens of 2 diopters, or 20 in.
focus, to effect the conversion ; a Leitz l/10th-in., the focus of
which is about 2*75 mm. (so that it is really a l/9th-in.), requires
8 diopters, or 5 in. focus ; and a Watson " Parachromatic '
l/12th-in. (actually a l/14th-in. of N.A. 1*30) requires a lens of
10 diopters, or 4 in. focus. I have not experimented with any
stronger lenses, nor do I think that this arrangement would be
of much use with such.
M. A. AINSLIE ON AN ADDITION TO THE OBJECTIVE. 573
Even if we have to sacrifice a little of the aperture of the lens,
however, it seems to me that there is a distinct field of utility
for this method of conversion. The effect on the definition, at
any rate in the centre of the field, of the additional lens is ex-
tremely small ; and with a l/12th-in. oil-immersion, treated in
this way, I have been able to get clear and strong resolution
of Amphipleura Lindheimeri in styrax, which, though not an
exhaustive test for a water-immersion, yet requires a pretty
good lens to give a really good image.
The useful limit of N.A. for a lens treated in this way is, I
think, about 1*15. It is not very likely that the full aperture of
the objective would be available, when one considers that the
full N.A. of an oil-immersion treated in this way is something
like 1*29 out of a possible 1'33, and that no water-immersion has
so far been put on the market, even apo chromatic, with a greater
N.A. than 1*25. If we are content, however, to sacrifice a little
of the margin of the lens, we can get a good water-immersion of
about the aperture named, which should be useful for occasional
use at any rate, when it is not worth while going to the expense
of a proper water-immersion objective.
It is a somewhat unfortunate, though unavoidable, circumstance
that the introduction of the additional lens shortens the working
distance, considering the limited working distance already
possessed by the average oil-immersion ; at the same time, the
l/12th-in. alluded to above will work through a cover-glass as
much as 0'20 mm. thick, and it is easy to obtain cover-glasses
thinner than this ; and it appears to me that it is only on tem-
porarily mounted specimens, such as films of living bacteria,
and the like, that one would want to use a water-immersion, the
great superiority of an oil-immersion on any permanently mounted
object being undeniable.
For biological, medical, and other work that requires the
examination of living objects, I think there is a real sphere of
usefulness for this method of conversion. But at the same
time, it should be noticed that the advantages of the method
are more pronounced if the oil-immersion objectives employed
are of medium power, and a l/10th-in. is certainly more
suited to the additional lens than a l/12th-in.
The conversion of an oil- into a water-immersion is particularly
useful when it is desired to examine living bacteria on a dark
574 M. A. AINSLIE ON AN ADDITION TO THE OBJECTIVE.
ground. It sometimes happens, when an oil-immersion is used
for this purpose, that the cover- glass has an unpleasant knack
of sticking to the front lens of the objective ; with a water-
immersion this difficulty is absent. iVlso, there is the distinct
advantage that it is easy to remove the water if it is desired
to examine the object with a dry lens, whereas this is by no
means an easy matter in the case of oil. The performance of
the Zeiss l/7th-in., used as a water-immersion, upon living
objects on a dark ground is especially good, though the Leitz
l/10th-in. is not far behind.
In the case of an oil-immersion, it is well to have the additional
lens fitted as close to the back lens of the objective as possible ;
there is no difficulty in doing this, as it is usually the practice of
makers to supply a ' funnel stop ' to which the optical part
of the objective can be screwed. If the stop is removed, and
the additional lens fitted in its place, so as to be close to the
back lens when the optical part is screwed on, the effect on the
magnifying power is not serious, and can be disregarded. In
the case of the Leitz 1/lOth-in., for example, the objective in
its normal state has a focal length of 2"75 mm., and is a l/9th-in. ;
with a lens of + 8 diopters in position immediately behind the
back lens, the focal length is 3 mm., and the objective becomes
a l/8th-in.
For dark-ground work, of course, the aperture must be reduced
to something like 0*85, with the dark-ground illuminators of the
present day ; and we may either fit a separate " funnel stop "
with a small lens in it, giving this aperture, or use the funnel
stop as it stands, and fit the lens in rear of the objective mount.
This, of course, reduces the power rather more than the other
arrangement, but this is not serious, as sufficient power can be
obtained by the use of a deeper eyepiece.
It should be noted that when the oil-immersion has been
converted in this way to a water-immersion, it becomes sensitive
to variations in the thickness of the cover-glass, though not to
the same extent as a dry objective ; the draw- tube will as a
rule be able to deal with this, but if more correction is required
it can be obtained by means of additional lenses, in the manner
described above for dry objectives.
I have left to the last, principally because it is more inter-
esting than practically useful, what is, from the " brass and
M. A. AIXSLIE ON AX ADDITION TO THE OBJECTIVE. O/O
glass " point of view, perhaps the most remarkable use to which
the additional lens can be put.
This is the conversion of a dry objective into an oil-immersion.
In the great majority of cases this cannot be done, not only
because it is too radical a change for most objectives, but because
the working distance is as a rule too great to admit of oil-contact.
But there are certain objectives of comparatively low power,
and small working distance, with which it is possible. The
matter only occurred to me a day or two ago, so that I have not
had the opportunity of trying the experiment with more than two
lenses ; with one of these, however, a 6-mm. Holos of the earlier
construction, having an N.A. of 0*84, I succeeded fairly well.
The additional lens required is a concave of — 10 diopters ;
with this, though the field is much curved, and good definition
can only be obtained in the centre, the effect is quite good.
It will be realised that the substitution of oil for air between
the front lens and the cover-glass is optically equivalent to the
thickening of the cover-glass so as to fill the wThole space between
the object and the front lens : it might be expected, therefore,
after wThat has been said, that the power of the additional lens
required would be considerable ; and I doubt whether the effect
could be obtained with a l/6th-in., except perhaps with one
of very short working distance.
The advent of the Zeiss l/7th-in. oil-immersion drew atten-
tion to the better resolution given by an oil-immersion over that
given by a dry objective of the same aperture ; but I did not
expect that this would hold good with such an arrangement as
that here described. I was much surprised, therefore, to find
that it was possible to resolve A. Lindheimeri with a solid axial
cone of illumination, the longitudinal and transverse striae being
quite plain with a compensating eyepiece 16*5. In this specimen
the striae run about 70,000 to the inch, and it is a very severe
test, under the conditions of illumination mentioned, for any
dry lens ; it is, of course, too hard for the 6 mm. Holos in its
dry state, the aperture being insufficient. The introduction
of the convex lens increases the N.A. to about 0'89 ; but I think
it is safe to say that no dry lens of this aperture would effect
the resolution with central light, though a much smaller aperture
will suffice with oblique light. In this case, then, the conversion
to an oil-immersion affords a distinct gain.
576 M. A. AIXSLIE ON AN ADDITION TO THE OBJECTIVE.
I have also tried to effect the conversion in the case of a Holos
4 rnm. of N.A. 0'95 ; but in this case it was impossible, even with
lenses of a total power of 18 diopters, which is far too powerful,
and upsets the objective altogether.
This application of the additional lens, therefore, I think is of
theoretical interest, but hardly of practical value.
I think that this device of the additional lens is worthy of
extended trial, both for the purpose of correcting for the
thickness of the cover-glass, and for the conversion of an oil-
immersion into a water-immersion. I shall be gratified if it
should prove of use to any one in practical work, and should
be glad to hear that some one has taken it up.
Journ. Quekttt Microscopical Club, Ser. 2, Vol. XII., No. 77, November 1915.
577
NOTES ON DIATOM STRUCTURE.
By A. A. C. Eltot Merlin, F.R.M.S.
{Read April 21th, 1915.)
I venture to bring to your notice a very beautiful form of
tertiary structure which I have recently found on a variety of
Aulacodiscus Comberi from Oamaru. The valve is on a styrax
type-slide of 230 forms from that locality and is covered with
a network of dark, well-defined secondaries, except on the parts
occupied by the large primaries. Each of the dark secondaries
has been found to be split up into three or four parts by a bright
cross-bar arrangement. This structure requires a good oil-
immersion objective and a very considerable magnification to
render it readily discernible, but it is in no way a glimpse object,
and when well seen reminds one of the bridges of bright matter
that are frequently observable crossing the umbrae of sunspots.
Photograph No. 1 exhibits clear indications of the structure
in question, x 2,150 diameters, although it cannot be photo-
graphed as plainly as it can be demonstrated visually. Inci-
dentally the photograph serves to prove the fact that with a
power of 2,150 diameters there is no excess of " empty magnifica-
tion," when employing a good lens of 1*4 N.A., for few will
comfortably see the structure therein without the aid of a low-
power magnifier.*
Two other photographs are sent herewith for your inspection.
These were secured under the following circumstances. Mr.
Nelson wrote to me that he had discovered that Coscinodiscus
Simbirskii, which with ordinary transmitted light resembles Cos-
cinodiscus asteromphalus, looks like Actinoptychus splendens when
* The photographs referred to in this paper contain details of such
a nature that only a drawing could adequately represent them for
purposes of reproduction.
Journ. Q. M. C, Series II. — No. 77. 32
578 A. A. C. ELIOT MERLIN ON DIATOM STRUCTURE.
examined with dark-ground illumination and a rather small stop.
This led me to search my Coscinodiscus genus circle slide for
the diatom mentioned. Although this could not be found, another
form was noted appearing with transmitted light as in photo-
graph No. 2 (x 295), while with dark-ground illumination a
beautiful radiating structure, somewhat resembling A. helio-
pelta, was revealed, which photograph No. 3, taken at the same
magnification, inadequately represents. Print No. 2 fails to
show a fine dotted structure which exists all over the valve
and can be detected in parts of No. 3. Print No. 2 should make
the identification of this specimen easy from its very marked
peculiarities.* These photographs were taken with a 16-mm.
apochromat of 0'35 N.A. and a x 6 projection eyepiece.
In connection with diatoms as test-objects there is an interest-
ing point, to me at least, on which I have been able to find no
definite information in the microscopical works in my possession.
I am alluding to the exact period during which the fine structure
of the diatom valve was first employed as a test-object. Are
we approaching the centenary of its discovery, a discovery
which has perhaps influenced more than any other the progress
towards perfection of the modern microscope stand and its
optical parts ? The oldest work on the microscope in my library
is the Microgr aphia Restaur ata, published in 1745.| This makes
no mention of diatoms, so that it may be taken for granted
that Dr. Hooke did not include " diatom-dotting " amongst his
' ' Wonderful Disco veries by the Microscope ' ' therein detailed. George
Adams published the fourth edition of his Micrographia Illustrata
in 1771 and also failed to include diatoms amongst the numerous
objects described in his interesting book, although many quaint
aquatic organisms are dealt with at considerable length, even
including ' a new sort of animalcula found in an infusion of
* C. Ludovicianus (Rattray) from Jutland.
f Dr. Robert Hooke, M. A., F.R.S. (1635-1703), Micrographia,or some
Physiological Descriptions of Minute Bodies made by Magnifying
Glasses, with Observations and Inquiries thereupon. The first edition
was published in London, 1665.
A. A. C. ELIOT MERLIN ON DIATOM STRUCTURE. 579
blue-bottles." We may thus assume that diatoms had not at
that period appeared on the scene to trouble the optician ' ' at
the Sign of Tycho Brahe's Head, No. 60, in Fleet Street, London."
Then who was the first man to dot the first diatom ? * Possibly
Dr. Goring, who, " is said to have discovered that the structure
of certain bodies could be readily seen in some microscopes
and not in others. These bodies he named test-objects ; he then
examined these tests with the achromatic combination before
noticed, and was led to the discovery of the fact that the pene-
trating power of the microscope depends upon its angle of
aperture " (vide Quekett's Practical Treatise on the Use of the
Microscope, second edition, p. 38). f Be this as it may, several test
diatoms are beautifully figured on PL 9 of Quekett's book, and
it is instructive to note that P. angulatum shown therein is the
Humber form with smoothly rounded outline and not the species
now known as P. quadratum, which, I am told, was the original
true P. angulatum as first found and named. Of course " diatom-
dotting ' was far advanced in Quekett's time. He recom-
mends the Navicula hippocampus as an excellent test for a l/4th-
inch objective-glass, stating that it should" show distinctly both
sets of lines or dots by oblique illumination." The younger
members of this club may not realise that first-class l/4th-inch
objectives made in 1850 have apertures slightly exceeding 0*7 N.A.
and will cleanly and clearly dot P. angulatum with axial critical
* Extract from Messrs. Sollitt & Harrison's paper read before the
British Association at Hull, 1853 :
" We in Hull first discovered the delicate markings on their silicious
coverings and pointed them out to others as the proper tests for lenses.
The first of the Diatomaceae on which the lines were seen was the
Navicula hippocampus of Ehrenberg. . . . This discovery was made
early in 1841, when specimens were sent to the Microscopical Society of
London . . . also to Mr. Smith, Mr. Ross, Messrs. Powell & Lealand.
M. Nachet in Paris and Professor Baily in America, the whole of
whom at once saw the excellency of those objects as tests for the
microscope. Indeed they are without doubt to the microscope what
the close double stars are to the telescope." — E. M. Nelson.
f First edition published 1848.
580 A. A. C. ELIOT MERLIN ON DIATOM STRUCTURE.
illumination, but such lenses were much more expensive than those
made to-day of equal, or superior, optical performance. Still,
it is as well to bear in mind that in 1850 thoroughly well-corrected
dry achromatic lenses up to 0*90 N.A. were obtainable (Powell's
l/16th-inch of that date has the last-mentioned aperture), and
were capable of resolving most of the present well-known tests
with the exception of the A. pellucida, this being first resolved
(according to Dr. Carpenter) by one of Powell & Lealand's
water-immersion objectives which that firm commenced con-
structing in 1868.
Jvurn. Qiuketl Microscopical Club, tier. 2, Vol. XII., No. 77, November 1915.
581
A NOTE ON THE SLIDES OF FISSIDENTACEAE IN
THE Q.M.C. CABINET.
By G. T. Harris.
(Read May 'loth, 1915.)
Communicated by Clarence J. H. Sidwell, F.R.M.S.
In Dixon's Student's Handbook of British Mosses the Fissi-
dentaceae of Great Britain comprise fourteen species and about
five well-marked varieties. Of these fourteen species eight
are represented in the Cabinet of the Quekett Microscopical
Club, and of these eight four at least are rare, and several very
rare. Fissidens exilis is the smallest of our native species and
is often found accidentally among some gathering of quite
another moss when examination takes place at home. There
is no difficulty in recognising it owing to its minute size and
non-bordered leaves. Fissidens viridulus is very slightly larger
than exilis, but has the leaves distinctly bordered with a narrow
cartilaginous border, which is usually lost at the apex ; the
variety Lylei, however, may be confused with exilis, as it is
very minute and has no border except on the sheathing laminae,
indeed it has been made a separate species by some authors.
It has been proposed to unite the species viridulus, pusillus, and
incurvus under one specific type, as intermediate states are
often met with. Fissidens incurvus var. tamarindifolius also
at one time had specific rank, but is now generally accepted as
a variety of incurvus. It is usually found sterile and has a quite
distinct facies when growing, that readily assures it recognition.
582 G. T. HARRIS, NOTE ON THE SLIDES OF
On closer examination the broad, distant leaves are quite dis-
tinctive.
Fissidens algarvicus (Solms.) was first recorded for the British
Isles by Mr. G. B. Savery at Silverton, S. Devon. It has later
been found near Cheltenham. Originally found in Portugal,
it appears to reach in England its most northerly limit. It is
interesting to note that a very closely allied species, Fissidens-
Orrii (Lindb.) (= F. tequendamensis, Mitt.), was recorded in
1854 from Dublin. Dr. Braithwaite pointed out the suspicious
proximity to the locality of the Glasnevin Botanic Gardens,
and certainly the species so far has not been refound, so is ex-
cluded from the British Moss Flora.
Fissidens bryoides is at once the commonest and most variable
of our species. The border is usually strong and continuous
to the apex, where are a few minute denticulations. It varies
considerably in size from a quarter of an inch to an inch or more
in height. It is densely gregarious, and it is not difficult to
recognise it by its general habit and habitat after a little experi-
ence. The form inconstans has the fruit sometimes terminal,,
at other times lateral, but its leaves and structure remain
fairly true to type.
Fissidens Curnowii was originally described by Schimper as
a variety of bryoides under the name caespitans, but Mitten
later raised it to specific rank as Fissidens Curnowii in honour
of W. Curnow, who apparently first discovered it in England
in 1868. Mr. H. N. Dixon in his Student's Handbook of British
Mosses gives it an intermediate position as a sub-species. It is
a rare species and the few records for it are from near the sea in
the south-west of England, though it has been recorded from
comparatively northern stations.
Both Curnow and Ralfs describe their localities as aquatic.
My locality in Sidmouth is a damp, not wet, sandstone cave,
FISSIDENTACEAE IN THE Q.M.C. CABINET. 583
and I should scarcely have regarded it as an aquatic species
comparable with rivularis or crassipes. It is a handsome moss,
usually fruiting profusely, and thickly matted with purple
radicles, though these are not so abundantly developed in the
young plants as in the older.
Fissidens rivularis, a truly aquatic moss, was originally found
by Mr. E. M. Holmes at Hastings in 1884, and this has hitherto
been the only British station. Some time ago I was fortunate
in adding a second station near Sidmouth, which appears to be
identical in physical conditions with Mr. Holmes's original one.
It occurs on rocks kept constantly wet by dripping water, and
in deep shade. Often it is quite hidden by an overgrowth of some
freshwater algae, and the fruit appears to be rare. The broad
yellow nerve and border, with its aquatic habitat, sufficiently
indicate it.
Fissidens polyphyllus is another more or less aquatic species.
The slide of this moss was already in the Quekett Microscopical
Club collection, and was sent to me with other slides of mosses
for verification by the Hon. Curator, Mr. Sidwell. No locality
is given, but it occurs very rarely in North Wales, Devon and
Cornwall. The fruit appears to be extremely rare, and has
perhaps only once been found, by M. Camus near St. Rivoal
in France. It is always barren in England, or at least has not
been found fruiting.
Fissidens taxifolius is a very common species on stiff argil-
laceous soils, and is one of the most easily recognised of the
Fissidentaceae. These comprise the various species of Fissidens
at present represented in the collection of the Quekett Micro-
scopical Club. I am hoping, however, that it may be possible
to add other species at a later date, possibly to make up the
entire series.
The genus is a very natural and distinctive one owing to
584 G. T. HARRIS, NOTE OX SLIDES OF FISSIDENTACEAE.
the bifarious arrangement of the leaves, and especially to the
curious sheathing laminae, so characteristic of the Fissiclentaceae.
Many theories have been advanced to account for the conduplica-
tion, and if the one that regards it as being originally a stipule
that has become adnate to the nerve by one of its margins is
the correct theory it certainly opens up a very interesting vista
of evolution.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII. , No. 77, November 1915.
585
FURTHER NOTES ON THE CULTIVATION OF
PLASMODIA OF BADHAMIA UTRICULARIS.
By A. E. Hilton.
{Read May 25th, 1915.)
A year ago I called your attention to a method of cultivating
plasmodia of Badhamia utricularis on bread, with occasional ap-
plications of a solution of ammonium phosphate and cane sugar ;
and my paper on the subject appears in the Journal for November
last. In the discussion which followed the reading of the paper
two points were raised which I could not reply to without further
investigation.
One of these was an inquiry by our Secretary as to whether
plasmodia of this particular species of Mycetozoa can be obtained
by cultivation of spores ; the answer to which is, that it is
possible, but not always easy. In the Journal of Botany for
January 1901 there is an account of an experiment on the point,
made by the late Mr. Arthur Lister, which ended successfully
after difficulties by the way had been overcome. In that experi-
ment spores of B. utricularis were moistened with boiled water,
and spread on slices of scalded fungus (Stereum). In six weeks'
time, after various vicissitudes, minute plasmodia were seen
under a microscope with a 2/5th-in. objective, and in another
fortnight or so a larger plasmodium was obtained, which after-
wards grew to a considerable size, part being dried off into
sclerotium for subsequent use, and the remainder forming
sporangia. It is to be noticed that in using Stereum Mr. Lister
relied upon natural rather than artificial food, the scalding of
the fungus being no doubt for the purpose of destroying any
organisms likely to upset the experiment.
The other question was raised by our President, who inquired
whether plasmodia fed by the artificial method introduced by
me could form sporangia. This point was clearly of import-
ance, involving as it did the crucial question as to whether, and
to what extent, such feeding affected the specific integrity of
586 A. E. HILTON ON THE CULTIVATION OF PLASMODIA.
the fundamental protoplasm. Again I found that the answer
to the question was in the affirmative, but with certain reserva-
tions. On February 19th last a plasmodium of B. utricularis-
was started by reviving a fragment of sclerotium, and this I
treated, throughout the whole course of its development, with
nothing but bread and water, and the chemical solution, in-
cluding calcium phosphate, which I added at Mr. Grundy's,
suggestion, with a view to supplying the lime usually found in
the sporangia of Mycetozoa classified as Calcarineae. For some
weeks, owing to low temperatures, growth was slow, but on the
weather becoming warmer, it increased considerably, and finally
on May 5th, when the atmosphere became close, with a thunder-
storm impending, the plasmodium changed into a quantity of
sporangia.
There are, however, striking differences between these spor-
angia and those produced in natural conditions. The shape is
similar, but instead of being of the usual cinereous hue, they are
mostly a dull purple-black ; others being of a cinnamon-brown
colour, and some of a pale biscuit tint. All are sprinkled with
white crystalline particles. The sporangium walls, usually
very thin and fragile, are hard, thick, and chippy ; and there is
no distinguishable capillitium. Stranger still, the sporangia
are only about half the ordinary diameter ; in other words,
about one- eighth of the usual size. The spores, generally bright
brown and spinulose, are smooth and almost colourless ; but
they are of the usual dimensions, if not, on the average, slightly
larger, and in other respects appear to be perfectly normal.
The characters on which the classification is based are thus
altered in nearly every particular ; the only permanent feature,
if there is one, being the specific spore-plasm. The result shows
what remarkable powers of adaptation the plasm possesses,
how precarious the present basis of classification really is, and
how impossible it is to define a species without a deeper know-
ledge than we yet possess of the specific character of the plasm
on which all the activities of physical life depend.
Journ. Quckett Microscopical Club, Ser. 2, Vol. XII., No. 77, November 1915
587
HYDRODICTYON RETiCULATUM.
By James Burton.
(Read May 2oth, 1915.)
Last autumn I had the good fortune to obtain the freshwater
alga known as the Water-net, Hydrodictyon reticulatum, or
utriculatum, for both names are used.
It occurred in immense quantity in the lake in Kew Gardens
and was brought to my notice by Mr. Traviss, who at the "Gossip"
meeting in September told me there was a plant in great amount
in the lake at Kew, and that it was like one of those loofahs
used in baths — it seemed to me a capital description, and I at
once realised that it was Hydrodictyon, and visited the scene
next day. Prof. West says it is a very rare plant in Britain, but
several authors say it is found fairly frequently in the south
and south-east of England. I do not know of it having been
found at any of our excursions, and though probably known
by name to many, it is most likely that few have seen it. I have
a page, evidently part of an article, in Dr. Cooke's handwriting
which gives some information about it. He savs : " The
Water-net is one of the earliest enumerated of the Freshwater
Algae in Britain. Its characteristic form enables figures to be
instantly recognised, and thus we are without doubt able to
assert its presence in 1691, when it was figured in Plukenet's
Alma Gestum (PL 2-1, f. 2) and again by Bobart in the 3rd vol*
of Morison's Hortus Oxoniensis in 1699. Ray includes it in his
" Synopsis " in 1724 as Conferva reticulata, and says that it was
found at that time in ditches, about Westminster and Hounslow."
Dr. Cooke then gives a number of instances in which it is referred
to by various writers, including Hassall in 1845. He then says :
,; Recent localities have not been recorded, in fact it is very
desirable that we should know the present stations of such an
easily recognised plant, which this year appeared in such quan-
tities in a small pond in the pleasure ground at Kew Gardens
588 JAMES BURTON ON HYDRODICTYON RETICVLATUM.
at the end of June, and scarce a fragment to be seen in the
middle of July." Unfortunately there my page comes to an
abrupt end, but as there are several interesting points about
this alga, it may be worth while bringing them to the notice of
the Club.
Owing to various characteristics which are not found in any
other alga, the genus Hydrodictyon has a sub-family to itself
and there is only one species. It consists of a saccate, net-like
object which ranges in size from very small, almost microscopic
dimensions up to a length of several inches, four, six and even
more. The cells of which the net is formed also vary very much
in size ; in the young ones they are quite minute, when first
recognisable from 8 to 10 ft in diameter only, but enlarge so
much in growth as sometimes to reach a length of 1 cm., say
two-fifths of an inch. The cells are approximately cylindrical
in shape and are arranged with their ends in contact, usually three
meeting at such an angle as to form typically hexagonal meshes,
but meshes with fewer or more boundary cells are- not uncommon.
They have a somewhat thick cell-wall, and inside a layer of
protoplasm, in which the green chlorophyll is diffused, not
collected into definite chloroplasts as is usual in algae.
The centre is filled with cell-sap. There are very numerous
and quite typical pyrenoids in the protoplasm, each consisting
of a central body, with a layer of starch grains on the outside ;
these may be considered reserve food material. At the com-
mencement of reproduction they disappear, and are obviously
used up during the process. There is also a quantity of fine
starch grains in the protoplasm, these being used for the purposes
of life and growth. Many nuclei are present in each cell.
The first point to notice is that the organism as a whole is
what is known as a coenobium ; it is, perhaps something more
than what is known as a colony, because the individual cells are
actually attached to one another, and form an association,
but certainly they are not greatly dependent on each other.
Each component cell is an individual, and carries on its living
functions independently ; for its own benefit solely it assimilates,
respires and reproduces, and were it separated from its fellows
would still be able to exist. We might then be inclined to
inquire what advantage the plant gains from the association
of so many units. One advantage is, that if the composing cells
JAMES BURTON OX HYDRODICTYOX RETICULATUM. 589
were separate, and sank to the bottom of the water, the}7 would
be liable to become overwhelmed in the mud and debris, while
in their present condition they would rest on the bottom without
danger of being covered up. It may also be noticed that an
organism formed like the water-net. when it is in active life
under the influence of warmth and light, excretes gas, and forms
bubbles, which are entangled in the meshes and float the whole
colony to the surface where it obtains better light and purer
water. Another advantage may be that the separate cells,
being for a time very small, would be liable to be taken as food
by various small aquatic animals, a fate to which they are
much less subject when combined into a larger body. Many
of the filamentous algae not usually looked upon as composed
of individuals, as coenobia in fact, are so in reality. This is the
case, for instance, with the well-known Spirogyra ; here each
cell of the filament if separated would be able to carry on its
vital functions, and probably the chief advantage it gains from
its form is something of the kind already mentioned.
But this brings me to the next point of interest in the water-net.
In Spirogyra and almost all other freshwater algae, multiplication
very largely takes place — in many species there is no other
method of propagation — by means of what we may call vegeta-
tive reproduction. A cell grows till it reaches its maximum
size, a wall is then formed across it and the one large mature cell
becomes two smaller young ones which gradually grow, and the
process is repeated. Now in Hydrodictyon there is no division
of a cell. You may examine any number of plants, each con-
sisting of perhaps thousands of cells, and you will never find one
undergoing cell-division. The cell begins quite small and grows
till it reaches what is a very large size for such an organism,
but it never gives rise in this way to another. From this a
singular result arises. The net is born, as we may say, with a
given number of cells, and through its life it consists of only the
same number and indeed of the identical ones which it had
originally. If owing to injury a part of the net is destroyed, it
is not replaced, the deficiency cannot be made good.
Another unique fact is the method of reproduction ; no other
alga has the same in detail. In the non-sexual method — which
is, I think, the most usual and is indeed the only kind of which
I have had actual experience — a small complete net consisting,
590 JAMES BURTON ON HYDRODICTYON RETICVLATUM.
it may be, of some thousands of cells, is formed inside each of the
members of the original net, which is reproducing. The process
takes place in this way. The pyrenoids disappear and the
protoplasm collects round each of the numerous nuclei, these
then divide repeatedly, until the whole becomes an enormous
number of spherical zoogonidia ; there may be from 7,000 to
20,000 of them in a single cell. In this they " swarm," as it is
called, i.e. they have a tremulous motion, not moving from
place to place to any extent, but just vibrating. There is some
uncertainty as to whether the gonidia have cilia ; one account
says they have four, most say two, and one account — I think
it is in Kerner — says they are not completely separated from
one another, but remain attached by a thread of protoplasm.
I do not think this is correct and believe they are actually
separate for a time, they then become oval instead of spherical
and attach themselves to one another by the ends, and gradually
in each mother-cell a complete young one is thus formed.
In the meantime the mother-cell wall gelatinises, and this goes
on so that by the time the young net is complete there is scarcely
any of the wall remaining, and soon it is entirely diffused and
the young one is set free. Some of the books tell us that a slit
is formed in the mother-cell and the young net escapes through
that, but I have not seen this occur, and think that the des-
cription applies to another circumstance — namely, the sexual
reproduction. This I have not observed, but stated shortly
the method is as follows : A much larger number of minute
reproductive bodies than in the previous case is formed. From
30,000 to 100,000 of them arise in the parent cell ; each of these
gametes has either two or four cilia. They issue from the
parent cell through a slit in the wall, enclosed in a vesicle formed
from the inner layer of the cell, and, becoming free in the water,
conjugate in pairs. The resulting zygospore sinks to the bottom.
It may germinate at once, but usually divides into two or four
parts which become resting spores — they are known from their
shape as polyhedra ; after some months they give rise indirectly
to small nets, which then give rise to larger ones of the usual
character. It may be noticed that there is no true sexuality
in the cells — or individuals — of which the net is formed. Any
cell may give rise to either sexual or non-sexual reproduction
according to circumstances. Klebs (I think it is) has stated
JAMES BURTON OX HYDRODICTYON RETICCLATU.V. 591
that non-sexual reproduction occurs when the water is clear
and there is abundance of chemical food material present with
appropriate temperature and light — in fact with favourable
vegetative conditions — while under less favourable conditions,
and with the presence of organic matter, decaying plants and so
on, in the water, there is a tendency for sexual reproduction to
take place. And he states that either condition may be readily
brought about at will, with plants grown under observation.
Perhaps not the least interesting fact about Hydrodictyon is
the manner of its occasional appearances. After being plentiful
on one occasion it will totally disappear, and for perhaps several
years nothing will be seen of it. Then again, owing to no
particular cause which is understood, it has another outbreak,
and the water from which it has been absent for long is again
filled with it. These outbreaks are known in some parts as the
" breaking of the meres," and by other similar terms. I knew
that in times past Hydrodictyon frequently appeared in the
lake in Kew Gardens and for many years — more than thirty,
I believe — looked out for it in vain. During all this time I only
found one very small and unsatisfactory specimen. Then last
autumn a tremendous outbreak occurred, the water was so full
of it that at the lee end of the lake the Hydrodictyon was massed
together to such an extent that it was impossible to get good
examples. Two boats were on the water, with men gathering
it in with rakes and piling it in heaps on the shore. In rather
less than four weeks I again visited Kew, and though diligent
search at every part of the lake was made, not a single specimen
could be found. Prof. West in speaking of this phenomenon
in regard to various other algae says '; they usually consist of
species that are normally present in the waters." But that can
hardly be said in this case ; normally it is impossible to find an
example of Hydrodictyon in the lake at Kew.
Personally I cannot suggest any better explanation of the
cause of the phenomenon than I gave once before. Speaking
of a similar outbreak of another alga it was said : "Of course in
some form they must always be present in the places in which
they occasionally appear so abundantly ; but the causes which
enable them to multiply in this manner seem to be unknown.
It cannot be a seasonal increase alone, such as we have in flower-
ing plants, which at the proper time develop and then die
592 JAMES BURTON ON HYDRODICTYOX RETICULATUM.
away. In that case the ' breaking of the meres ' would be an
annual occurrence, or nearly so, with more tendency to regularity
than it seems to have. Clearly there must be some simultaneous
occurrence of several favourable circumstances which does not
frequently arise : possibly some special type of weather and
some narrow range of temperature at a particular season would
be factors in the required conditions."
Jottrn. Quekell Microscopical Club, Ser. 2, Vol. XII., No. 77, November 1915.
593
VARIOUS INSECT STRUCTURES.
By Edward M. Nelson, F.R.M.S.
{Read May 25th, 1915.)
The wing of Agrion pulchellum (Neuroptera) is not only a wonder-
ful, but a particularly interesting microscopical object. The
membrane, which in life reflects beautiful colours, is double,
each part being bordered by a stout rim edged with formidable
saw-like teeth. The surface of the wing is divided into com-
partments by nervures which are peculiar ; for the transverse
bars, as well as four of the longitudinal bars, have on one edge
thorns just like those on a sloe-bush, and on the other edge
saw-like teeth ; there are three other longitudinal ribs, which
have saw-like teeth on one edge and very fine teeth on the other,
but no thorns.
This beautiful microscopical object forms an excellent test for
low powers, " loups " or simple microscopes.
At one part on the edge of the wing there is a dark-coloured
compartment, inappropriately called the " stigma." This really
is a pocket, the two membranes being separated from one another
at this point by some brown cellular tissue, the saw-edged
borders of the membranes being kept apart, thus forming an
opening. Obviously, then, the " stigma ' is an apparatus for
producing a sound, much in the same way as the " bull roarer "
of our childhood. The " stigma ' can be seen readily by the
naked eye, as it measures 1*1 mm. x 0'5 mm.
If we replace the low power by a 1/2 inch, a careful examina-
tion of the border of the wing reveals a delicate hair between
the teeth of the saw (fig. 1).
These hairs are minute, the largest one found measured only
23 fx in length and 2 fx in breadth ; but on other species of Dragon-
flies they are larger and more easy to demonstrate. These hairs
spring out of circular rings, after the manner of most hairs on
insects, and not like the small ones on the membrane of the
blow-fly's tongue, which have no rings. While on this subject of
Journ. Q. M. C, Series II.— No. 77. 33
594 EDWARD M. NELSON ON VARIOUS INSECT STRUCTURES.
insects hairs, a careful examination of the small hairs upon the
wing of a wasp will show that they are twisted like the tusk of
a narwhal (fig. 6).
The hairs on a bee's wing are somewhat similar, but not so
much twisted, while they have no ring. Those on the wing of
a saw-fly (Tenthredo) issue from a boss. The hairs on the
ovipositor of Phalangia are more interesting. This ovipositor
has some thirty or forty white and brown transverse stripes ;
the hairs upon it are of the ordinary kind with a ringed base,
7*/.
4-
except those upon the two last terminal stripes, where the hairs
are larger and the ringed base is ornamented with a circle of
very minute hairs ; the hair itself is tubular and has a fila-
mentous end. At the side of these hairs there is a sort of minute
prong, which might be thought a hook, but is, I think, a cut or
opening in the side of the hair (fig. 4, termination of hair not
drawn). At the end of each of the two lobes of the ovipositor
is a small boss covered with small hairs. These hairs have no
ring bases and are blunt-ended, probably open at the top ; but
they have internal ring (not spiral) structure somewhat like an
EDWARD M. XELSOX ON VARIOUS INSECT STRUCTURES. 595
artery (fig. 5) . A 1/4 th inch will be necessary to demonstrate these
structures. The saw on the wing of Agrion is a comparatively
bold structure, but if we examine the mandibles of a gad-fly
(Tabanus bovinus) we shall find upon one edge the most wonderful
saw in the world, having ten to sixteen thousand teeth per inch
on it, while the other edge is the keenest blade in existence
(fig. 7). As a point of " microscopy " these teeth on the saw on the
the lancets or mandibles of this insect form the most delicate
optical test I know. This is a matter of some importance, as
Podura test-scales are now not to be had — for, sad to say, one
may pay 20s. for a slide of Podura scales and not find a single
test-scale upon it ! If any member of the Club has an objective
that will show these saw-like teeth with a large or full cone he
should take great care of it, as it may be some time before he
finds another that will do so. A 1 J inch * that will demon-
strate these teeth at the point of the mandible with axial
illumination must be a good lens. This test, however, is not
confined to low powers, for high powers such as a l/4th or
a l/6th that will show the teeth with a large working aperture
cannot have much wrong with them. *As the aperture of the
substage condenser is opened a point will be found when, owing
to spherical aberration in the objective, the image of the teeth
will vanish suddenly. This test rivals in sensitiveness all others
with which I am acquainted, and it is scarcely necessary to add
that a precise adjustment of tube length is necessary ; but it is
important to bear in mind that with a small or moderate sized
cone it is no test at all.
The teeth are coarser at the point, where they count 10,000
per inch, and finer at the base of the mandible, where they
count 16,000 per inch. Those on the mandible of Haematopoda
fluvialis are still finer and count from 15,600 to 19,200 per inch.
The stout hairs on the palpi of this insect issue from a delicate
cup. The hairs on the wing of Tricho'pteryx atomaria have
secondary hairs on them ; a secondary hair measured in length
1*1 /./, thickness 0*18 /a = yiiVoo" mch. This beautiful micro-
scopical object cannot be seen with an objective of less than
0'58 N.A. These few instances are mentioned to show that
a critical examination of the hairs of insects is not only a
* Some H inches are engraved 2 inches; such lenses should also
show them.
596 EDWARD M. NELSON ON VARIOUS INSECT STRUCTURES.
useful, but also a fascinating branch of microscopical study.
We will now pass on for a moment to the Vespa crabro, or
hornet. If its sting be examined with a 2/3rd inch objective
the barbs, A, fig. 2, will be seen ; B is a tube, and C a razor blade.
Fig. 3 shows the sting in section. The fine tubules, three below
the last barb and one below each of the others, will be seen. The
breadth of the sting in fig. 2 is 110 fx, the width of the razor blade
33 fx, the length of a barb 17 /x, the length of a tubule 25 //,, and its
width 4*2 fx. If the sting happens to be well placed the exit
pore of a tubule may be caught. It is probable that these stings
are homologous with the saws in the ovipositors of insects.
Instead of barbs there are bold saw-like teeth, which, unlike
those in a carpenter's saw, go round the side of the saw — the
holes for the emission of lubricating or poisonous fluids are
numerous and much easier noted than those on the sting of a
hornet. The ovipositor of a dragon-fly is a good example.
In conclusion, I would draw your attention to the pygidium
of a flea. If the right- and left-hand edges be examined a hole will
be found ; this is an Eustachian tube. The apparatus corresponds
to the drum of an ear, and must like it have an air passage to
equalise the pressure on either side. Now look at the base of
the haltere in a blow-fly, where a similar tube will be easily seen.
Joum. Quekett Microscopical Club, Ser. 2, Vol. XII., Nc. 77, November 1913.
597
THE DETERMINATION OF MINERALS UNDER THE
MICROSCOPE BY MEANS OF THEIR OPTICAL
CHARACTERS.*
By J. W. Evans, D.Sc, LL.B. (London),
OF THE IMPERIAL COLLEGE OF SCIENCE AND TECHNOLOGY,
AND BIRKBECK COLLEGE, UNIVERSITY OF LONDON.
(Read June 22nd, 1915.)
Communicated by the Hon. Editor.
Plates 35-37.
A petrological microscope is not merely employed for the
study of details too small to be seen by the unaided eye, it is
also an instrument for the investigation of the optical properties
of minerals, by means of which they may be distinguished
from one another.
Kotation of Nicols or Stage. — For this purpose the microscope
must be so constructed that the minerals can be examined
between crossed nicols. A Nicol's prism or nicol permits only
light vibrating in a particular direction to pass. Two nicols
are said to be crossed when these directions of vibration are at
right angles to each other. It is also necessary that either the
stage or the nicols shall be capable of rotation round the micro-
scope axis. For many reasons the rotation of the nicols, while
the stage remains stationary, is to be preferred ; and when an
immersion lens is employed with loose material, it is essential
that there should be no relative movement between the stage
and objective. The mechanical difficulties of construction in
instruments of this type add, however, considerably to the
expense, with the result that in the majority of petrological
microscopes in use the nicols are fixed, while the stage rotates.
I have, accordingly, assumed throughout that such an instru-
* A brief communication to the Geologists' Association on similar lines
was made by the author in 1909 (see Proc. Geol. Assoc, vol. xxi., 1909,
pp. 79-94). The Quekett Microscopical Club is indebted to the
Geologists' Association for their courteous permission to use the blocks
illustrating this paper.
598 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
ment is employed. At the same time tlie complication of the
phenomena caused by the rotation of the object renders a
systematic procedure, such as I shall describe, very desirable, if
mistakes are to be avoided.
Centring. — In such an instrument an arrangement for centring,
by which the axis of the microscope can be adjusted so that it
may pass through the centre of the stage, is absolutely necessary.
The centring may be carried out by placing a rock-slice in focus
under the microscope, noticing the point round which the object
seems to rotate, and bringing this to the centre of the field by
means of the centring screws.
Nose-fiece. — The mechanism for centring should be applied to
the nose-piece and not to the stage, since it is the former which
is most liable to be displaced, especially if a double or triple
nose-piece for interchanging objectives be employed. The use
of a clutch, first employed, I believe, by Nachet, by which
objectives can be rapidly attached or removed, is preferable.
Kecently a lateral sliding arrangement has been introduced, but
I do not think that it possesses any points of superiority over
the clutch.
Movements of One Nicol. — One or both nicols should be
capable of separate rotation, and one at least should be capable
of being rapidly thrown out of the course of the light so that
the observation may be made with one nicol only. The nicol
that remains in position should be so placed that it allows light
vibrating right and left to pass, for with the usual disposition
of the mirror the light reflected from it is polarised so that
more of it already vibrates in this than in other directions.
There is consequently an appreciable saving of light with this
position of the nicol.*
It is usual to remove the upper nicol or analyser, but F. E.
Wright recommends the removal of the lower nicol or polariser.
This has the advantage that the field is not affected in focus
or position, when the nicol is moved in or taken out.
* To ascertain in what direction light traversing a nicol vibrates,
the nicol should be inserted alone and a rock-slice containing biotite
flakes showing strong pleochroism placed on the stage and rotated
till a flake is in the position of maximum darkness. The direction
of the cleavage of this flake will then be parallel to that of the vibration
of the nicol.
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 599
The upper nicol usually slides in and out of the lower part
of the tube above the objective. This has the advantage of
not obstructing the field, but there are two objections to this
plan. In the first place the nicol cannot, as usually constructed,
be rotated, and secondly, it does not allow of the insertion of
a quartz wedge in focus. For this reason the upper nicol is
sometimes placed above the eye- piece. In this case it should
be thrown in or out by means of a hinge. The common
arrangement by which it is removed altogether results in loss
of time in adjustment when it is replaced. The nicol that
rotates should be provided with catches or ""clicks" to arrest
its movement in the crossed position, and in that at right
angles to it, in which its direction of vibration is parallel to
that of the other nicol.
Cross Wires. — The cross wires will be parallel to the directions
of vibration of light traversing the nicols respectively when in
their normal position.
The cross wires should not be spider lines, which are easily
broken by the insertion of the quartz wedge or other accessories,
but should be ruled on a glass plate. As this is apt to get
covered with dust, the eye-piece should be made to screw apart
immediately above the plate so that it may be easily cleaned.
Slots. — The microscope should be provided with one or more
slots for the insertion of various accessories. In this country
slots are placed diagonally to the cross wires. On the Continent,
however, they are sometimes right and left, and accessories
connected with polarization effects, such as quartz wedges,
gypsum plate, or mica steps, must be constructed accordingly.
This is a matter that requires attention in buying and working
with foreign microscopes. The slot is usually placed immediately
above the objective. Wright, however, prefers to have it below the
stage (but naturally above the lower nicol), so that the insertion
of a plate or wedge, like that of the lower nicol referred to above,
does not affect the field. Another course is to have the slot
at the focus of the eye- piece, in which case the upper nicol must
be placed above the eye-piece. This arrangement has the
advantage that a quartz wedge, or other accessory, placed in
the slot is in focus. The same result can also be obtained
with a slot below the stage, if the condenser be placed in position
and slightly lowered.
600 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
Means should be provided to close the slot, when not in use.
Fine Adjustment. — The fine- adjustment screw should be
graduated on its circumference so as to show the number of
microns by which the microscope is raised or depressed. A
micron is the thousandth part of a millimetre and is the most
convenient unit of length for microscopical purposes. A com-
plete turn of the screw will usually correspond to 500 microns,
and in that case a scale parallel to the axis should be provided,
divided into half millimetres, so that by means of the double
graduation comparatively large movements may be accurately
measured.
Illumination. — The best illumination is that from the sky. If
artificial light must be resorted to, a gas mantle provided with
a cylinder of ground or milk-white glass, or a small arc light
similarly treated, should be employed. If, however, the illumi-
nation is very strong, the lower nicol may be injured by over-
heating. If there is any danger of this, a suitable glass vessel
containing water may be interposed.
Objectives. — Although a 1-in. objective is used for most pur-
poses, a lower power is convenient in the case of rocks of coarse
texture, while for very fine structures and minute crystals and
inclusions a l/4th-in. or still higher power must be employed.
I have myself found a twelfth very useful.
These close objectives are also required for the simultaneous
examination of different directions in a crystal, a subject I shall
deal with later.
Rock-slices. — A good rock-slice should range between twenty
and thirty microns in thickness, but with comparatively large
transparent minerals much thicker sections may usefully be em-
ployed, while those with fine structures or which are comparatively
opaque should be as thin as they can be made. It is important
that a section should be as uniform in thickness as possible,
It is preferable that a rock-slice intended for research should
have no cover- glass and that its surface and sides should be free
from Canada balsam. It may then be covered in turn by liquids
with different refractive indices (see p. 626) or subjected to
microchemical tests.
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 601
The Object-Image.
Under this heading I include all observations in which the
object itself appears in focus in the field of the microscope.
Examination in Ordinary Light. — The crystal section should
be brought into the centre of the field, so that it lies beneath the
intersection of the cross wires, and the stage rotated till the index
reading is zero. The outline and any other characteristic features
should now be traced or sketched, surrounded by a circle repre-
senting the margin of the field, and a scale of microns with the
numerical value of the magnification added. The scale is con-
structed with the assistance of an eye-piece micrometer calibrated
from a stage micrometer. The position of the cross wires is
shown by short radial lines drawn inwards from the circumfer-
ence (figs. 1-3). The right end of the right and left cross wire is
marked with 0° outside the circle, because it is the direction of
the vibration of the nicol, when one only is inserted, and the
positions of the other ends of the cross wires by 90°, 180° and
270°, in the same cyclical order as the graduations on the
stage, which are usually contrary to those of the hands of a
watch.
The stage is now rotated, and as the trace of a face, cleavage
or other rectilineal marking, such as a line (representing a plane)
of inclusions, comes into a position of parallelism with the right
and left cross wire, the latter should be inserted in its new position
in the sketch as an interrupted line across the field, and dis-
tinguished on its right extremity outside the circle by the
index reading of the stage (figs. 1-3). As each line comes twice
into the right and left position, it will have readings at both
ends, which will differ by 180°. All these readings will follow
each other in the sketch in their cyclical order.
Extinctions. — Both nicols are now inserted in the crossed
position and the stage rotated. If the crystal section remain
dark through a complete rotation, the crystal section is either
isotropic or cut at right angles to the optic axis of a uniaxial
crystal. If it continue uniformly faintly illuminated, it is at
right angles to an optic axis of a biaxial crystal. Usually,
however, it will be dark at four points in the rotation when the
directions of vibration of light traversing the crystal section
602 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
are parallel to those of the nicols and therefore to the cross
wires.*
These positions of darkness are known as extinctions, and they
are distant 90° from one another. If the section is exactly at
right angles to a plane of crystal symmetry or parallel to an
axis of crystal symmetry, in which cases it is at right angles to
a plane of optical symmetry, the position of extinction will be
identical for all colours and will be characterised by complete
darkness. At the same time the crystal outline will usually
be symmetrical to the cross wires, which will now indicate the
directions of vibration, both in the nicols and the crystal, for all
colours. In such cases, the extinction is said to be symmetrical.
If, on the other hand, the section does not occupy such a position
the extinction will be different for different colours, or, as it is
usually expressed, is dispersed. Unless the dispersion be very
small, there will never be complete darkness with white or other
composite light, but it may always be obtained by employing
monochromatic light.
There is usually some difficulty in determining the position
of maximum darkness corresponding to the true position of
extinction, even where there is no dispersion, or where mono-
chromatic light is employed, and resort has been had to various
methods of obtaining an exact result.
One of the simplest of these is to rotate the stage towards
the position of extinction alternately from opposite cyclical
directions and to note the readings on each side where the same
degree of darkness has been obtained. The mean of several
pairs of careful observations will approximate closely to the
index reading corresponding to the true position of extinction.
In another method, which has been investigated in detail by
F. E. Wright, | the crystal is first placed in the approximate
position of extinction obtained in the manner already described,
and then one of the nicols is rotated through a small but definite
angle and the degree of illumination that results is carefully noted.
The nicol is next rotated in the opposite direction through
exactly the same angle on the other side of its normal position.
* According to one view of the direction of the vibration of light
in crystals this is not strictly true ; it is, however, in any case sufficiently
accurate for practical purposes.
t Am. Journ. Sci., Series IV., vol. xxvi., 1908, pp. 349-3G8, 379.
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 603
If the illumination in the two cases be the same, the supposed
position of extinction is correct. If not, the nicol is restored
to its original position, and the stage is rotated slightly towards
the direction in which the darkness was the greater. The
same test is then again applied, and, if necessary, the process
is repeated, till the rotation of one nicol through equal angles
in both directions produces the same result.
The angle through which the nicol must be rotated is that
which will produce a faint illumination for rotation in one direc-
tion. It is usually between half a degree and two degrees. As
a rule it would be sufficient if a graduation were provided showing
a rotation of a nicol through J, 1 and 1J degrees.
Where the position of extinction is the same for all colours,
this method may be applied either with monochromatic or
white light, the latter being preferable, not only because the
illumination is greater, but also because, when the true position
of extinction has not been obtained, the two directions of rota-
tion of a nicol give different interference colours.
Wright has devised a bi-nicol ocular in which the results of
the rotation of two upper nicols in opposite directions may be
observed simultaneously.* A similar effect is obtained by the
insertion of plates of right- and left-handed quartz, which rotate
the nicol through equal angles in opposite directions. This is the
principle of the Bertrand eye-piece, but in its usual form the
plate is so thick, 2'5 mm., that it rotates the light through a
large angle, about 60° for sodium light and greater or less amounts
for light with shorter or longer wave length. If it be reduced
to a thickness of forty microns corresponding to a rotation of
1° for sodium light, much greater accuracy is obtained, both
with monochromatic and white light, f
Wright's bi-quartz ivedge plate, a combination of wedges and
plates of quartz, enables a rotation of any convenient amount
in opposite directions to be obtained.!
In all these determinations greater accuracy can be secured
by increasing the illumination, but care must be taken that
the lower nicol is not injured by over-heating (see p. 600).
It is unnecessary to dwell here on the other methods which
* Loc. cit., pp. 374-376, 379.
f S. Nakamura,Centr. f. Min., 1905, pp. 267-279.
% Am. Journ. Set., Series IV., vol. xxvi., 1908, pp. 377-380.
604 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
have been introduced at different times for the same purpose,
as few if any of them are so exact as those which have been
described.
When the stage is in the exact position of extinction — in other
words, when the directions of vibration in the crystal are parallel
to those of the nicols and therefore to the cross wires — the posi-
tion of the latter is indicated in the sketch by thick lines traversing
the whole field, and the index reading is inserted on the right
extremity of the right and left cross wire, while the other
terminations of the cross wires are distinguished by the corre-
sponding angular numbers differing by 90° (see fig. 1).
Pleochroism, etc. — The light vibrating parallel to each direction
of vibration is differently affected by the structure of the crystal.
The velocity of transmission of the vibrations parallel to one is
greater than that of those parallel to the other and the index of
refraction is consequently less in the case of the former. At
the same time the absorption of light may differ considerably
both in the colour selected and in amount. For an examination
of these differences the crystal is observed with only one nicol
in place, and the stage is rotated in turn into each of the positions
in which a direction of vibration is parallel to the right and
left cross wire. This, as we have seen (p. 598) , should be the
direction of vibration of the nicol that is retained. The surface
of the mineral, whether it is rough or smooth, and its luminosity
and colour are observed in each case and noted in the sketch
at the right end of the thick line representing the corresponding
direction of vibration.*
Sometimes the surface of the crystal is distinctly rougher in
one position than in the other. This indicates that there is
considerably more difference between the refractive index of
the light vibrating parallel to the right and left direction and
that of the medium in which the section is mounted (Canada
balsam or whatever it may be) in the former case than in the
latter. This phenomenon is well seen, when Canada balsam is
the medium, in calcite and the carbonates isomorphic to it,
as well as in the colourless micas. It causes a characteristic
twinkling effect when the lower nicol is rapidly rotated.
Character of Directions of Vibration. — We now proceed to
determine the character (or sign) of the extinctions or directions
* See fig. 1.
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 605
of vibration in the crystal section — that is to say, to ascertain
which of these is the direction of vibration of light with the
greater velocity, and which that of light with the less velocity.
The character of the former direction of vibration or extinction
is said to be fast ( — ) and that of the latter slow ( -j- ).
Relative Retardation. — We can also determine at the same
time the amount of the relative retardation — in other words, the
distance by which the slow- moving vibrations have lagged
behind the faster. Both are delayed in traversing the section,
but the former more than the latter. Relative retardation is
usually measured in micro-millimetres or millionths of a milli-
metre. The character of any definite direction in a crystal
section, e.^.tone of its longer sides, is also said to be fast, or slow,
according as it coincides or makes an angle of less than 45°
with the fast, or the slow, directions of vibration, and to be
neutral when it bisects the angle between them.
For the purpose of making these determinations the section is
brought into a position of extinction and then the stage rotated
through 45°, so that the directions of vibration in the section are
diagonal to those in the nicols. This is known as the diagonal
■position. One of the directions of vibration in the section will
then be parallel to the slot. To ascertain which it is, the stage is
rotated through 45° till the direction which was parallel to the
slot is in the right and left position, when the index reading will
be that of the direction required. The same reading may be
obtained by adding or subtracting, as the case may be, 45° to or
from the index reading in the diagonal position. For instance,
if the slot is in the position shown in fig. 3, 45° will be
added.
In the diagonal position the vibrations which pass the lower
nicol are resolved along the two directions of vibration in the
section. If there were no relative retardation between the
vibrations in these directions, thev would on emergence re-
combine to form, once more, vibrations parallel to the direction of
the vibration of the light when it left the lower nicol and would
therefore be extinguished by the upper nicol. As a result, how-
ever, of the relative retardation this is no longer the case, and
the various colours of the spectrum are transmitted in different
degrees, so that the compoimd tints known as interference colours
are obtained. These are dependent on the amount of the relative
606 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
retardation, which is usually approximately the same for all
the colours of the spectrum.
Within certain limits every amount of relative retardation is
distinguished by its own characteristic interference tint between
crossed nicols, and these tints are practically the same for the
majority of minerals, though the thickness required to give rise
to a particular colour varies greatly for different minerals and
according to the direction in which the same mineral may be
cut. It is only in those minerals in which the relative retardation
varies for different colours that unusual or anomalous colours are
seen. These minerals are so few in number that the occurrence
of their characteristic anomalous colours furnishes a ready means
of distinguishing them. The indigo- blue seen in many thin
sections of chlorite is a familiar example.
The normal interference colours commence with complete
darkness at zero relative retardation and pass through grey,
white, yellow, orange, and red, at the end of which the relative
retardation reaches 550 micro- millimetres. These constitute the
■colours of the first order. Then follow purple, violet, blue,
green, yellow and red up to a relative retardation of 1,100. These
are the colours of the second order. Every addition of 550 micro-
millimetres corresponds to another order with a similar suc-
cession of colours, which gradually become more complex till
they are only represented by delicate shades of green and pink,
and with a relative retardation of about 4,000 micro-millimetres
they slowly pass into white light, the ' white of the higher
orders." The colours are said to be lower or higher according
as they result from a less or greater amount of relative retar-
dation.
If one nicol be rotated through a quarter turn so that the
directions of vibration of the two nicols are parallel, the com-
plementary colours are seen, which commence with white and
pass through brown, red and blue to the yellowish green that
marks the end of the first order at 550. The second order passes
through yellow, red and blue to green again, and in the higher
orders the colours gradually fade away through pinks and greens
into white light exactly as with crossed nicols.
The amount of the relative retardation in a crystal section
may often be roughly estimated directly from the interference
colours between crossed and parallel nicols by comparison with
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 6()7
a table or lithographic plate of the colours with the correspond-
ing relative retardations, but in determining colours so much
depends on the idiosyncrasy of the observer and the character
of the light that such estimates can only be relied on within very
wide limits. In the smoky atmosphere of a London winter, for
instance, the blue of the second order under crossed nicols appears,
as Mr. T. Crook pointed out to me, to pass directly into greenish
yellow without anything that could be definitely characterised
as green intervening.
The birefringence may be denned as the relative retardation in
a unit of distance. The relative retardation is, accordingly, equal
to the product of the birefringence of the section and its thick-
ness, the distance traversed. It can be shown that, if the same
units are employed for both relative retardation and distance
traversed, the birefringence is equal to the difference between the
refractive indices of the two directions of vibration.
If then k be the relative retardation, I the thickness of the
section, d the birefringence and /x and v the refractive indices
in the fast and slow directions, we have k = I d = I (v — li).
In the case of a section of quartz 21 microns thick, cut parallel
to the optic axis, the indices of refraction are 1*514 and 1'553
and the birefringence 0*009, which is the relative retardation in
microns after traversing one micron. Accordingly h = 21 x 0*009
= 0*189 of a micron.
If, however, the relative retardation be expressed, as usual, in
micro-millimetres, it will, foi- the same thickness, be numerically
a thousandfold greater. This value of the relative retardation
may be denoted by K, and tne corresponding value of the bire-
fringence, that is to say the relative retardations in micro-
millimetres after traversing one micron, by D, which will be, in
the same manner, numerically a thousand times d, the value in
homogeneous units. D may be referred to as the birefringence
in millesims, where a millesim is a unit equal to 0*001. The
equation then becomes K = I D. In the special case which
has been taken, the birefringence is 9 millesims, so that K =
21 x 9 = 189 micro-millimetres. This procedure has the advan-
tage of avoiding small decimal amounts.
The birefringence varies according to the direction in which
the section is cut in the crvstal. The value given in text-books
is the maximum birefringence, that found in sections cut parallel
608 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
to the optic axis in uniaxial crystals, and to the optic axial plane
in biaxial crystals. The actual birefringence in a section may
be anything between this and zero.
The maximum birefringence in millesims may be obtained
from the value in homogeneous units found in text-books by
moving the decimal point three places to the right.
The Quartz Wedge. — If the relative retardation is to be de-
termined at the same time as the character of the directions
of vibration, a quartz wedge or mica steps must be employed.
The quartz wedge is cut in this country with its length parallel
to the optic axis, which is the direction of vibration of the light
propagated with the least velocity. The length is therefore
slow ( -f- ) while the width is fast ( — ). As wedges are some-
times cut in different directions, the character of the length
should be engraved on the glass as shown in fig. 3.
The wedge should be graduated so as to indicate the relative
retardation at different points (see fig. 3). It should be inserted
in focus (see p. 599), otherwise the colours will be blurred from
overlapping and the graduation be invisible.
If the wedge be inserted in the slot between crossed nicols,
when there is no birefringent mineral in the field or none which
is not in the position of extinction, the normal succession of inter-
ference colours is seen commencing at the thin end of the wedge,
where, however, the black and darker grey are usually missing
on account of the difficulty of preserving the thin end from
abrasion.
If, however, there is a birefringent mineral present in the
diagonal position, so that the directions of vibration of the light
traversing it are parallel and at right angles to the slot, and
therefore parallel to those of light traversing the quartz wedge,
the relative retardation of light traversing both the mineral and
the wedge will be the combined effect of the relative retardation
in each.
If the directions of the slow ( + ) and fast ( — ) vibrations
respectively in the mineral are the same as in the quartz
wedge, the colour seen at any point where the two are superposed
will correspond to a relative retardation equal to the sum of the
relative retardations of both. This may be referred to as
the additive position. As the length of the quartz wedge is slow
( + ), the direction in the crystal which coincides with that of
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 609
the slot must evidently in this case also be slow ( -f- ). If on
the other hand the slow direction of the wedge correspond with
the fast direction in the crystal section and vice versa, the resulting
relative retardation will be equal to the difference of relative re-
tardations in the two, and they may be said to be in the subt) 'active
position (fig. 3). In this case the direction in the crystal section
parallel to the length of the wedge and therefore to the slot will
be fast ( — ). If the relative retardation of the crystal section be
within the limits of relative retardation shown by the wedge,
there will, as the wedge is advanced through the slot in the
subtractive position, be ultimately seen a black band traversing
the crystal at right angles to the length of the wedge. This
marks the point where the relative retardation in the wedge
exactly neutralises that in the crystal section, being equal to it
but opposite in character. The relative retardation shown in
the graduation of the wedge at the point where the black band
appears must therefore be that of the section also.
If the mineral gives rise to very high relative retardation and
shows only pale pink and green tints or the white of the higher
orders, except on the margin where bands of the lower-order
colours are visible, the character of the section may most easily
be determined by noticing how these bands move when the
wedge is inserted. If they move inward from the margin, the
mineral and the wedge are in the subtractive position ; if out-
wards towards the margin, in the additive position. In such
cases it is frequently desirable to employ an especially thick
wedge with a comparatively large angle. It sometimes happens
in the case of minerals with high birefringence that, even when
the wedge is inserted in the subtractive position and the relative
retardation at its thick end exceeds that of the mineral, no
definite black band can be recognised, but when the wedge is
inserted up to a certain point, irregular lines appear, which
are too thin for the colours to be recognised, and when the
wedge is pushed still farther in, they disappear. The mean of
the values of the relative retardations of the quartz wedge at
the points where these lines appear and disappear may be taken
as that of the mineral under examination.
In all cases of difficulty in making this determination it is
best to use strictly parallel light.
With strongly pleochroic minerals the black band does not
Jourx. Q. M. C, Series II.— No. 77. 34
610 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
occur, as the excessive absorption of some or all colours in one
direction prevents the recombination of the vibrations to form
light vibrating parallel to the right and left cross wires. For
the same reason the interference colours of such minerals are
abnormal. As already stated, a similar result is obtained also
where the birefringence — and therefore the relative retardation —
varies considerably for different colours (see p. 606). In either
case it is, however, generally possible to estimate with a fair
amount of accuracy the central position from which the
relative retardation with its corresponding colours increases in
both directions.
Pleochroic sections may be referred to as slow-dark and fast-
dark according as the character of the direction of maximum
absorption is slow or fast. The latter case is comparatively rare,
and when it occurs, as in aegyrine, riebeckite, arfvedsonite,
apatite, and andalusite, is of considerable diagnostic value.
Similarly, where the colour varies considerably, crystal sec-
tions may be termed fast-red and slow-green, or as the case may
be. Where the contrast is between red on the one hand and
blue or green on the other, the fast vibrations are usually asso-
ciated with the former.
In the double quartz wedge (fig. 4) which I described in the
Mineralogical Magazine (vol. xiv. (1905), pp. 91-2) there are two
wedges, one with the length slow ( + ) and the width fast ( — ),
the other with these characters reversed. They have the same
angle and the same birefringence, so that when cemented by
Canada balsam side by side on a glass slip and inserted in
the slot between crossed nicols the colours stretch across the
two component wedges exactly as if they were one ; but if a
birefringent crystal section be in the field with its directions of
vibration parallel and at right angles to the slot, one side will
show additive effects and the other subtractive, so that the
existence of a small relative retardation is easily recognised, and
the amount of the relative retardation may be read off which-
ever direction of vibration in the crystal section is parallel to
the slot. It may be noted that the colour in one component
wedge opposite the black band in the other corresponds to a
relative retardation exactly double that of the crystal section
under examination.
All forms of quartz wedge should be carefully calibrated by
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 611
means of the dark and light bands which replace the colours
in mono-chromatic light. The error may be thus determined
within ten micro-millimetres.
Gypsum Plate. — If the relative retardation be very small it is
difficult to detect or measure it by a quartz wedge on account
of the imperfection of the thin edge of the latter. It is best
investigated by means of a gypsum plate, parallel to the clino-
pinakoidal cleavage, of such a thickness as to show the violet
corresponding to a relative retardation of 575 micro-millimetres.
A very small decrease in the relative retardation is sufficient to
modify the colour considerably and cause it to pass into purple
or red, while a slight increase changes it to indigo or blue.*
The gypsum plate is usually cut with its length parallel to
the fast direction.! It may be inserted in either slot or in any
other place in the course of the light between crossed nicols, but
always in a diagonal direction. If a crystal section with low
birefringence is now placed on the stage with its directions of
vibration parallel and at right angles respectively to this
direction, the colour of the plate will be seen to be modified
so as to indicate an increase or decrease in the relative retarda-
tion. In the former case the vibrations in the crystal parallel
to the slot will be fast, in the latter slow. J
To determine the relative retardation of the crystal section,
that of the combination is determined by means of the quartz
wedge and the position of the black band on it. The stage is
then rotated through an angle of 90° and the determination
repeated. Half the sum will be the relative retardation of the
* Gypsum plates are, however, usually made to show the red of the
first or second order, which is not so sensitive to variations in thickness
and therefore easier to produce of a practically uniform tint.
f A circular plate mounted in wood is to be avoided, for if it becomes
loose, as frequently happens, it loses its correct orientation. The
plate should be marked so as to show the numerical amount of the
relative retardation and the character of the length, as in fig. 5.
J In the case of small minerals with low relative retardation, which
are rendered inconspicuous by the bright light to which the gypsum
plate gives rise, it is better, if the construction of the microscope permits,
to insert the plate in a direction making only a small angle with the
cross wire. This diminishes the illumination due to the plate without
affecting appreciably the illumination and colour of the mineral under
examination (F. E. Wright, Am. Journ. Sc, series IV., vol. xxxv.,
1913, p. 66).
612 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
gypsum plate (which should agree with its previously ascertained
value) and half the difference that of the crystal section. If
the gypsum plate and quartz wedge are to be used together,
the former should be inserted in the lower slot, leaving the upper
for the latter ; the upper nicol would then be necessarily placed
above the eye-piece.
F. E. Wright has devised a useful combination of quartz wedge
and gypsum plate,* and I have employed the same idea in the
following manner (fig. 5). A quartz wedge is superposed on
a gypsum plate showing the sensitive tint, both being con-
structed with the usual orientation (see above), so as to leave
beyond the thin end of the wedge a square of gypsum which
may be used as an ordinary gypsum plate. The quartz will
show a black band where it exactly neutralises the gypsum,
and the same succession of colours in opposite directions from
this point, which is indicated by a line marked zero ; but
those on one side stop short a little before the colour of the
plate is reached. Every hundred micro-millimetres of relative
retardation on either side is shown by graduations. If the
direction of the crystal section parallel to the slot be fast ( — )
the black band will move towards the thick end of the wed»;e, if
slow ( + ), towards the thin end.
Mica Steps (fig. 6) consist of a succession of narrow cleavage
plates of muscovite with their length cut parallel to the trace
of the optic axial plane and therefore slow. Each strip should
have a relative retardation of a hundred micro-millimetres.
They are of different lengths, and when superposed form a suc-
cession of steps each large enough to cover the whole cone of
light in the lower slot, where they are usually employed, though
they are equally useful in the focus of the eye-piece, if the upper
nicol be placed above them. In either case they show a dis-
continuous series of colours corresponding to differences of one
hundred micro-millimetres. If they are inserted over a crystal
section it is easy to see whether the two show additive or sub-
tractive relations. In the former case the stage should be rotated
till the fast direction of the crystal section is parallel to the slot.
It may then happen that the crystal section is exactly neutralised
by one of the steps and must therefore have the same relative
* Journal of Geology, vol. x., 1902, pp. 33-35. See also Min.
Petr. Mitt. (Tschermak), vol. xx., 1901, pp. 275-6.
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 613
retardation. Usually, however, while one of the steps faite to
neutralise the section, the next higher will more than do so, and
neither will be completely dark. If they are equally bright,
the relative retardation of the section must be midway between
those of the two steps. If one be darker than the other the
relative retardation will be proportionately nearer to that of
the darker step. In this way it will be possible to estimate the
relative retardation to within twenty or thirty micro-millimetres.
If a further approximation be desired it may be obtained by
employing additional smaller mica steps divided into four portions
with twenty, forty, sixty and eighty micro-millimetres relative
retardation respectively. If the larger mica steps are inserted in
the lower slot, the smaller can be placed in the upper. In this
way it is possible to determine relative retardation to within
ten micro-millimetres and make estimations to within half that
amount.
Mica steps are one of the many useful pieces of apparatus
devised by Fedorov, but the description given above differs
from his directions in some details, having reference chiefly to
the amount of the relative retardation represented by each step.
Mica steps may be calibrated by reference to a quartz wedge
the errors of which have already been determined.
In order to obtain the birefringence of the section from the
relative retardation it is necessary to determine the thickness.
As this will usually involve the movement of the rock-slice it
is better postponed till after the " directions-image " has been
examined. For the same reason the determination of the
refractive index should also be deferred to a later stage.
The Directions-Image.
It is frequently desirable to examine simultaneously the
•optical properties of a number of different directions in a mineral,
so that a comprehensive idea of its optical characters may be
obtained. For this purpose the microscope is, in the manner
which will be described, converted into an optical instrument
in which every point in the image corresponds not to a point
in the object under examination, but to a direction along which
light traverses that object in parallel paths. Such an instrument-
may be conveniently described as a hodoscope or path viewer, a
614 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
term which is to be preferred to the word " konoscope " employed
by some authors.
If a microscope, from which the eye-piece had been removed,
were directed vertically upwards towards a cloudless sky at
night, the images of all the brighter stars within a certain distance
of the zenith, dependent on the angular aperture of the objective,
would be seen on the principal focal surface of the objective —
that is to say, its focal surface for light from an infinite distance.
Each of these images would be formed of light which had been
travelling by parallel paths, or in other words in the same direc-
tion, which would of course be different for different stars. By
day the whole field would be illuminated and every point in it
would represent light which had reached the objective from a
particular direction. If a mineral section were now interposed
close to the objective, every illuminated point on the focal
surface would represent a direction in the crystal section, which
would be determined by the construction of the objective, the
position of the point relatively to it and the refraction at the
surface of the section. The image thus obtained representing
different directions in a mineral may be described as the directions-
image, as opposed to the object-image in which the microscope
is focused on the object itself.
As it is inconvenient to direct the microscope to the sky, the
different directions in the mineral section are illuminated by
placing below the stage and above the mirror of the microscope
a condenser consisting of a convergent lens or system of lenses.
For this reason the directions-image is frequently referred to
as the "image in convergent light," an altogether misleading-
expression, since convergent light is habitually employed
with close objectives, when the microscope is focused on the
object itself, or in other words when the object-image is under
examination. In observing the directions-image it is usually
desirable to employ wide-angled objectives, so as to include
as many directions as possible, and the angular aperture of
the condenser must be at least as great.
The directions-image of small crystals, grains and fragments
may be examined in like manner, though the results are modified
by the varying effects of refraction at different points, unless
the medium in which the object is immersed has approximately
the same index of refraction as the object itself. The inter-
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 615
ference colours are also affected by the variations in the thick-
ness traversed, even by light moving in parallel directions.
The Bertrand Lens. — As the directions-image formed by the
objective is small and somewhat inaccessible, it is usual to
employ a Bertrand lens, a convex lens, which is placed, when
required, in the tube, and forms a secondary directions-image
in the focus of the eye-piece. The Bertrand lens is, as a rule,
inserted a short distance above the objective, but is sometimes
placed higher up, and then occupies only the centre of the tube,
so that a large portion of the object-image may, if desired,
be left visible. If this be done, the observer can, without losing
sight of the directions-image satisfy himself from time to time
as to the point on which the microscope is . directed and, if
desired, change from one portion of the crystal section to another.
The Bertrand lens should be capable of being focused by a
sliding movement along the axis of the microscope, and it is im-
portant that this movement should have sufficient range for the
purpose, which is not always the case.
The Becke Lens. — Instead of inserting; the Bertrand lens in
the tube, it is possible to obtain the same result more conveniently
by placing the Becke lens above the eye-piece. This is a convex
lens or system of lenses, similar to a Ramsden eye-piece, which
magnifies the directions-image formed in the Ramsden circle of
the eye-piece. It should have a focusing movement.
Isolation of the Directions-Image of a Mineral. — If the mineral
under examination is not alone in the field, it is desirable to
isolate it so that the effects of different minerals may not be
blended and thus interfere with one another.
This object may sometimes be attained by using a closer
objective and thus diminishing the extent of the rock-slice or
glass slip included in the field.
A more generally available method, however, is to cut off
all light except that reaching the mineral under examination.
For this purpose a diaphragm may be placed a little distance
below the condenser, which is adjusted so that the image of
the aperture in the diaphragm is focused simultaneously with
the object.
In some microscopes the iris diaphragm, attached to the
condenser for carrying out the Becke method of determining
the relative refractive indices of minerals in thin sections (p. 626).
616 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
may be employed.* In that case all that is necessary is to focus
the microscope on the object, and after nearly closing the dia-
phragm lower the condenser till the aperture in the diaphragm
appears in focus. The glass slip is then adjusted, if necessary,
so that the mineral to be observed is in the centre of the field
and the diaphragm opened or closed till the maximum area of
that mineral, but no portion of any other, is illuminated, f It is
scarcely necessary to add that the greatest care must be taken
to see that the nose-piece is exactly centred so that the object
remains in the illuminated area during the rotation of the stage.
The Bertrand or Becke lens is now placed in position and the
directions-image can be studied.
The same result can be obtained by placing a diaphragm at
any point above the object where a real object-image is formed,
provided of course that it is not affected by the conversion of
the microscope into a hodoscope. One of the following methods,
preferably the second, may be employed :
1. If the eye-piece be removed, an object-image can be formed
exactly at the upper end of the microscope tube by operating the
coarse or fine adjustment. The mineral selected for examination
is then brought into the centre of the field and a cap with a
•central perforation, not larger than the image of the mineral, is
placed on the end of the tube. If the eye be now placed close
to the aperture, the directions- image will be seen low down in
the tube in the position already described, illuminated only by
light which has traversed the mineral.
2. The eye-piece may be retained and the mineral to be studied
isolated by means of a diaphragm in the focus of the eye-piece.
The Becke lens is then placed in position and the directions-
image of the mineral, unmixed with other light, is seen.
3. If the Bertrand lens be employed, an object-image is
formed above it and below the eye-piece, and can be seen if the
eye-piece be removed. A diaphragm may be inserted here,
but the low magnification of the image is a drawback. A
diaphragm is frequently placed just below the Bertrand lens.
* In other instruments the iris diaphragm is so close to the condenser
that the latter cannot be lowered sufficiently to bring it into focus.
Another diaphragm must then be provided.
f Light traversing glass or other isotropic substances will not,
however, affect the result, if the nicols be crossed.
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 617
Iii that case to make the object-image coincide with the dia-
phragm, a lens, or a combination of a lens with the eye-piece, is
focused on the position of the diaphragm and the tube raised till
the object is seen in focus. The angle of the cone illuminated by
the condenser is, however, diminished by the elevation of the
objective.
I now proceed to describe some of the phenomena seen in the
directions-image, especially those which may be easily observed
in minerals in thin sections and afford important information with
regard to their optical characters, as well as the directions in
which they have been cut.
Interference Colours in the Directions-Image. — When the
directions-image is examined between crossed nicols it shows
in the centre of the field the same interference colour as that
seen in the object-image. From the centre outwards this passes
into other colours corresponding to different amounts of relative
retardation which may be greater or less than that in the centre.
The colours move with the stage as it rotates without sufferino-
•any change of configuration.
Isogyres. — At the same time the field is traversed by dark
bands or brushes, which constitute the isogyre* As the rotation
proceeds, this, as a rule, changes both its position and its shape
and from time to time leaves the field altogether.
When the stage is in the position corresponding to extinction
in the object-image, in other words when the vibrations in the
plane of the crystal section are parallel to the cross wires, the
isogyre passes through the centre of the field and is known as a
central isogyre (figs. 7, 8, 13, 16-21).
The visible portion of the isogyre consists in the majority of
cases of a single dark band, which usually expands towards the
margin of the field to form a less definite brush. This moves
four times across the field as the stage rotates, being usually
lost to view in the intervals.
In other cases the isogyre consists of two dark bands which
either meet in a cross or form the two branches of an hyperbola.
The following special types of central isogyres formed of a
single band may be distinguished.
A symmetrical isogyre is straight and parallel to one of the
* F. Becke, Min. Petr. Mitt. (Tschermak), vol. xxiv., 1905, pp. 1-34, and
Min. Mag. vol. adv.-, 1907, pp. 27G-80, and J. W. Evans, ib. pp. 230-3.
618 J. W. EVANS ON THE DETERMINATION OF xMINERALS UNDER
cross wires and therefore to one of the directions of vibration in
the section (figs. 7, 8 and 17). A section showing a symmetrical
isogyre is itself said to be symmetrical.
A symmetrical section is always cut at right angles to a plane
of optical symmetry, of which the central isogyre is the trace.
Every section of a uniaxial mineral is cut at right angles to a
plane of optical symmetry, while this is only exceptionally the
case wTith sections of biaxial crystals. If, therefore, every section
of a mineral in a rock section shows a symmetrical isogyre, we
may safely assume that the mineral is uniaxial.
As a general rule in biaxial crystals a central isogyre is curved
and oblique to the cross wires (figs. 16, 19).
A pseudosymmetric isogyre is straight, but is parallel not
to one of the cross wires, but to the line bisecting the angle
between them (fig. 18).
A pseudosymmetric section is only met with in crystals
whose optic axial angle is 90° and the normal of such a section
lies in one of the planes containing the optic normal and one
of the optic axes of the crystal.
If an isogyre is formed of two bars, but only one of these
passes through the centre of the field, the nature of the isogyre
and of the section is determined by the portion of the isogyre
which passes through the centre.
If the two bars meet at right angles in the centre and form a
cross, they are both straight and parallel to the cross wires and
therefore symmetrical. The section must accordingly have been
cut at right angles to two planes of optical symmetry and to
the line of optical symmetry in which they meet. In a biaxial
crystal this line is either a bisectrix or the optic normal. In
the latter case, the cross is somewhat indistinct and in crystals
with an optic axial angle approaching a right angle it becomes
unrecognisable. If a section of a uniaxial crystal show a central
cross, it is either cut at right angles to the optic axis, and therefore
to an infinite number of planes of optical symmetry, or it is
parallel to the optic axis. In the latter case, again, the cross
is indistinct.
The Movements of Isogyres. — The movements of a symmetrical
isogyre, when the stage is rotated alternately in opposite directions,
are symmetrical to the cross wire to which it is parallel, while
those of a pseudosymmetric isogyre are symmetrical in the same
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 619
way to the diagonal to which it is parallel. If the movements
are unsymmetrical, the isogyre must be so likewise.
If, when the stage is rotated, one of the ends of an isogyre
at the boundary of the field moves round the circumference
in the same cyclical direction as that in which the stage is
rotated, that end is said to be proximal. If it moves round
in the opposite direction or is stationary, it is distal. The
terms homodrom and antidrom are used by Becke, but they
are misleading, if a microscope with rotating nicols be employed,
and proximal and distal are accordingly more suited for general
use. The manner in which they are applied is illustrated in
figs. 7, 9-11 and 16-18.
An isogyre consisting of a single band has usually one end
proximal and the other distal. A proximal end is directed
towards the nearest optic axis, or, if it be practically equidistant
from the two optic axes, to the nearest bisectrix.
An isogyre consisting of two bars intersecting in a cross
has in biaxial crystals (fig. 13) two proximal ends opposite to
each other and two distal ends. If the centre of the cross repre-
sents a bisectrix, the proximal ends are directed towards the
optic axes and the bar to which they belong marks the trace of the
optic axial plane. The distal ends lie in the direction of the optic
normal. If the section is, on the other hand, cut at right angles to
the optic normal, the proximal ends point to the acute bisectrix
and the distal towards the obtuse bisectrix.
On rotation of the stage the cross breaks up into two hyper-
bolic branches, each with one proximal and one distal end. These
move away from the centre and may pass entirely out of the field.
In sections of uniaxial crystals cut at right angles to the optic
axis (fig. 21) the cross does not break up on the stage being rotated,
and the ends are stationary and therefore distal. The phenomena
:n sections parallel to the optic axis are similar to those in
sections at right angles to the optic normal in biaxial crystals.
The proximal ends are directed towards the optic axis, while
the bar with distal ends lies in the plane of optical symmetry
at right angles to the optic axis.
If the distal end of an isogyre move more rapidly than the
proximal end, the movement may be compared to that of a
pendulum. This happens when the proximal end is directed
towards an optic axis. If the section is symmetrical, either
620 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
it is at right angles to the optic axial plane of a biaxial crystal,
•or it is a section of a uniaxial crystal, which makes a very
large angle with the basal plane.
If both ends move at nearly the same rate, the isogyre passes
straight across the field, maintaining approximately its rectilinear
form and keeping parallel to one of the cross wires (fig. 11). This
is the case in sections of uniaxial crystals which make only a
moderate angle with the basal plane. It is not the only move-
ment occurring in isogyres of uniaxial minerals, as is commonly
supposed to be the case.
Longitudinal and Transverse Directions. — A direction of vibra-
tion (or extinction) is said to be longitudinal, when it is parallel
to the central isogyre where it passes through the centre, or
when it makes an angle of . less than 45° with it. The transverse
direction of vibration is that at right angles to the longitudinal
direction. If a central isogyre is diagonal, that is to say if it
bisects the angle between the cross wires, the directions of
vibration are neither longitudinal nor transverse:
The ends of a longitudinal direction nearest to the proximal
<and distal ends of the isogyre may themselves be described as
proximal and distal respectively.
In a central cross which breaks up into hyperbolic branches
when the stage is rotated, the horizontal or vertical bar with two
proximal ends marks the longitudinal direction, and in the
diagonal position becomes the axis of the hyperbola, if one be
visible (figs. 13 and 14).
If there be a central cross which does not break up, the section
is, as already stated, cut at right angles to the optic axis of a
uniaxial crystal, and all directions are longitudinal (fig. 21).
The Character of Isogyres and Sections. — The character (sign)
of a central isogyre is that of the longitudinal direction (see p. 605),
and the same character is attributed to the section itself. A
diagonal isogyre and its section are said to be neutral, for they
/can be neither fast nor slow, since there is no distinction between
longitudinal and transverse directions.
The determination of the character of sections in a rock-slice
enables us to form a conclusion as to the character of the mineral
as a whole.
In a uniaxial crystal the character of all sections is the same
.as the character of the mineral, which is that of its optic axis.
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 621
In a biaxial crystal the character of the greater number of
sections is the same as that of the mineral, which is that of its
acute bisectrix. The smaller this angle the more frequently
the character of sections coincides with that of the mineral.
A section with pendulum movement and higher relative retarda-
tion than most other sections of the same mineral with the same
thickness will always have the same character as the mineral itself.
A pseudosymmetric section indicates that the crystal is neutral,
in other words, that its optic axial angle is 90°, but only certain
sections of a neutral crystal are pseudosymmetric, and other
neutral sections do not necessarily belong to a neutral crystal.
The character of the longitudinal direction is best ascertained
in the object-image in the manner already described, but as will
be seen it may also be determined from the directions-image
itself.
To identify the longitudinal direction and its proximal and
distal ends in the sketch of the object-image, the stage should
be rotated till in the directions-image the central isogyre is seen
to coincide or make an angle of less than 45° with the right and
left cross-wire and have its proximal end to the right. This
may be termed the index position of the isogyre, for the index
reading will then give the position of the proximal end of the
longitudinal direction of vibration.
When the isogyre is in the index-position, the character of the
longitudinal direction may be determined by inserting a gypsum
plate in the slot (figs. 8 and 16). If this be done the isogyre itself
will assume the colour characteristic of the plate, but will be
bordered by higher colours on one side and lower colours on the
other. If the colours are lower on the same side as the proximal
end of the slot, the character of the longitudinal direction and
therefore of the isogyre and section will be the same as that of the
direction of the gypsum plate parallel to the slot. By the
proximal end of the slot is meant of course that nearest the
proximal end of the isogyre and of the longitudinal direction of
vibration. If the procedure already described has been fol-
lowed, this will be the right-hand end. If the colours are higher
on the same side as the proximal end of the slot, the character
of the section will be opposite to that of the direction in the
gypsum plate parallel to the slot.
For instance, if the slot be in the position indicated in figs. 8
622 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
and 16, and the colours be lower on the margin of the isogyre
farther from the observer as in those figures, the character of
the section will be the same as that of the plate parallel to the slot.
These methods apply both to uniaxial and biaxial crystals.
The inferences that can be drawn from the characters of one or
more sections with reference to that of the mineral have already
been described (pp. 620, 621).
Sections Perpendicular to an Optic Axis. — These may be re-
cognised in the object-image by the darkness in all positions *
in a uniaxial mineral, and in a biaxial mineral by a feeble
illumination which does not vary when the stage is rotated.
They show no relative retardation and are therefore neutral.
If a gypsum plate be inserted in the slot over the directions-
image of such a section of a uniaxial crystal, the black cross
in the directions-image will be represented by a cross of the
colour characteristic of the plate ; and if the mineral be of the
same character as the direction in the plate parallel to the slot,
the quadrants through which the slot passes will show higher
colours, and the other quadrants lower colours, while if it be of
the opposite character, the contrary will be the case. If a quartz
wedge or mica ladder possessing the same character as the
mineral be pushed progressively in, the rings of colour in the
former quadrants will contract, and in the latter will expand, and
if it possess the opposite character, the same phenomena will
occur in the alternate quadrants.
In biaxial crystals cut at right angles to an optic axis, the
isogyre always passes through the centre, and has two distal ends.
In certain positions it is straight and parallel to a cross wire and
lies in the optic axial plane. If then the stage is rotated through
45° towards the slot, the isogyre becomes a branch of an hyperbola
with its axis parallel to the slot (fig. 19). If a gypsum plate be
now inserted, the hyperbolic isogyre will show the interference
colour of the plate, and at the same time, if the crystal
have the same character as the direction in the plate parallel
to the slot, the concave margin will exhibit higher colours
* Isotropic crystals will also be dark in all positions in the object-
image, but the directions-image will show a uniformly dark field
instead of a cross, unless, as sometimes happens, the glass of the ob-
jective is in a state of strain, when a feeble uniaxial cross may be
visible.
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 623
(fig. 19), while the convex margin will exhibit lower colours.
If the crystal have the opposite character, the reverse will be
the case. The amount of the curvature of the isogyre in this
position gives some idea of the magnitude of the acute optic-
axial angle. If the isogyre be straight, the angle will be 90°
{fig. 18), while if it forms a right angle coinciding with two arms
of the cross wires, it is 0°. In this case the other branch of
the hyperbola coalesces with it, forming the cross characteristic
of a uniaxial crystal (fig. 21).
A very rough approximation to the optic axial angle, which
may be employed for determinative purposes, may be obtained
by taking the angular distance 6 round the circumference of the
field between the darkest point in one end of a branch of the
hyperbola and the nearest cross wire, and doubling it (fig. 19).
The result is usually too high, especially for medium angles, in
which the error may amount to 10°. F. Becke has shown how
a much more accurate result may be obtained,* and a still
more rigorous procedure is described by F. E. Wright. f
These methods may be applied even when the section is not
exactly at right angles to the optic axis, if the point of emergence
of the latter appears in the directions-image (fig. 20). Such
sections may be recognised in the object-image by the compara-
tively low relative retardation.
Sections showing a Black Cross ivhich breaks up on Rotation of
the Stage. — Unless the section be at right angles to an acute
bisectrix, the character of the longitudinal direction of vibration
(see p. 620) will be that of the crystal, and this will always be the
case if the section shows high relative retardation compared with
most other sections of the same mineral with the same thickness.
The black crosses seen in sections of uniaxial crystals parallel to
the optic axis and of biaxial crystals at right angles to the
optic normal are distinguished by the rapidity with which
they break up and leave the field when the stage is rotated.
Where the optic axial angle is small, sections at right angles to
the obtuse bisectrix resemble those at right angles to the optic
normal.
* Min. Petr. Mitt. {Tschermak), vol. xxiv., 1905, pp. 35-44; Min.
Mag., vol. xiv., 1907. p. 280.
j American Journal of Science, Series IV., vol. xxiv., 1907, pp.
332-341. In the same paper other methods are discussed.
624 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
In neutral crystals and in those in which the optic axial angle
differs but slightly from a right angle, the optic normal, as we
have seen, shows no cross, and those seen in sections at right
angles to the two bisectrics are indistinguishable.
If the optic axial angle is so small that both optic axes are
visible in the same section, the methods already described for the
case where one optic axis is present may be employed (fig 14).
Variations of Relative Retardation in a Directions-Image. — There
is usually a decrease in the relative retardation indicated by
the interference colours towards the proximal margin or margins
of the field, and this may be utilised to determine the position
of the longitudinal direction and its proximal end. For this
purpose the stage is rotated though 45° from the position of
extinction. Unless an optic axis is visible, the isogyre will
then have passed out of the field and the region of lowest
interference colours will mark the position of the proximal end
of the longitudinal direction (fig. 12). If the section be at right
angles to a line of optical symmetry, there will -be two opposite
regions of lowest relative retardation (fig. 15), and the line joining
them will be the longitudinal direction. This method is fre-
quently useful where the isogyre is indistinct.*
In doubtful cases the gypsum plate may be inserted, and then
the region that approximates most closely to the colour of the
plate will have the lowest birefringence and indicate the prox-
imal end and longitudinal direction. If this be at a point within
45° of the slot and the colour be higher than that of the plate,
the character of the section will be the same as the character
of the plate. If it be more than 45° from the slot, or the
colour be lower, the character will be opposite to that of
the plate. If both these conditions hold good, it will be the
same as that of the plate. In neutral sections the lowest
colour will be about 45° from the slot.
If the optic axis be in the field, the line joining it to the
centre will be the longitudinal direction. Some portions of
the field will then have a higher and others a lower colour than
the plate, and the colour in the centre of the field will determine
the character of the section, unless of course the optic axis is in
the centre of the field, when the character will be neutral (p. 622).
Theodolite Stage. — In recent years Fedorov has introduced
* J. W. Evans, Mia. Mag., vol. xiv., 1907, pp. 233-4.
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 625
the *' universal " or theodolite stage by means of which the
properties of light vibrating in different directions may be
studied in parallel light in the object- image of a single section
by rotating the latter on two or more axes. The subject is,
however, too extensive to be considered on this occasion.
Other Determinations.
The Thickness of the Rock-slice. — The only practicable method
of determining the thickness of an ordinary rock-slice is to select
a known mineral whose maximum birefringence is practically
constant and not too low, such for instance as quartz, orthoclase,
olivine, calcite and (for approximate results) an acid or inter-
mediate plagioclase. Search is then made for the section of this
mineral which shows the highest relative retardation, and it
may be assumed that its birefringence has as nearly as possible
the maximum value. Suppose the mineral to be quartz, with
a birefringence of 9 millesims (0'009), and the greatest relative
retardation observed to be 315 micro-millimetres. Then the
thickness of the section will be 315 -f- 9 = 35 microns.
The thickness should be determined, if possible, at several
points so as to obtain an idea of its variation in different parts of
the rock-slice. If the thickness of the rock-slice is not uniform,
that of the crystal section must be estimated from its position
in the slice as nearly as possible. The thickness should be stated
on the sketch, and indicated by the depth of the scale (fig. 1).
]f the thickness is not uniform, the amount of variation may
be indicated in the same way.
Determination of the Birefringence. — Knowing the thickness of
a crystal section and its relative retardation, we are able to
determine its birefringence by dividing the latter by the former.
For instance, if the section has a relative retardation of 340
micro-millimetres and a thickness of 28 microns, the birefringence
will amount to 340 -j- 28 = 12 millesims or 0*012.
A number of different crystals of the same mineral are dealt
with in this matter, and it may be assumed that the maximum
birefringence thus obtained falls but little short of the maximum
birefringence of the mineral.
The Refractive Index. — A knowledge of the index of refraction
of a mineral is a valuable means of recognition. In the case
Journ. Q. M. C, Series IT. — No. 77. 35
626 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
of a thin section in a rock-slice only relative determinations of
refractive indices are possible in an ordinary petrological micro-
scope, comparison being made either with the Canada balsam
or other medium in which the rock-slice is immersed, or with
an adjoining crystal.
For the Becke method a high power is employed, and the
cone of illumination is narrowed. This may be effected by
removing or lowering the condenser and inserting a card-
board slip with a hole one or two millimetres in diameter
twenty or thirty millimetres below the stage.* A slit of the
same diameter parallel to the boundary of the section may be
substituted. This is equally effective and does not cut down the
light to the same extent. The boundary surface between the
section and the medium or adjoining crystal must be at right
angles to the surface of the rock-slice. This can be verified bv
observing if it remains constant in position when the focus is
varied.
If now there be an appreciable difference between the re-
fractive indices on opposite sides of the boundary, one margin
of the boundary will usually be seen to be lighter than the field
in general and the other darker. If the objective be focused
on a point in the neighbourhood of the upper surface of the
section, the light margin of the boundary will be on the side
with the higher refractive index and the dark margin on that
with the lower refractive index. If the focus be gradually lowered,
these bands will be reversed in position.
In this way it is possible to determine whether the refractive
index of a crystal mounted in Canada balsam is higher or lower
than that of this substance. If, however, the crystal is un-
covered, and its margin free from balsam, it may be immersed
in a succession of films of liquid of different refractive indices
and its refractive index thus determined between comparatively
narrow limits.
If the crystal section be birefringent the observation should
be made with the lower nicol in position, and first one and then
the other direction of vibration in the crystal should be brought
into parallelism with the direction of vibration in the lower nicol.
In this way the indices of refraction parallel to both directions
of vibration may be determined.
* An iris diaphragm is often provided, and is more convenient.
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 627
If the directions of vibration of adjoining crystal sections
are parallel, exact comparison of the refractive indices corres-
ponding to each pair of parallel directions may be carried out
in the same manner. In other cases parallel nicols should be
employed and the stage rotated till their direction of vibration
bisects the angle between the directions of the pairs of vibration
the refractive indices of which are to be compared. In all
cases a comparison of the mean refractive indices may be made
by dispensing with the use of a nicol.
If a crystal or grain be immersed in Canada balsam or other
medium, such as a highly refracting liquid, or a larger crystal,
the relation between its refractive index and that of the sur-
rounding material may be determined by the Schroder van der
Kolk or " finger ' method. A condenser is employed and
placed close below the object, or the effects will be reversed.
One side of the illumination is then shaded, usually by the
finger placed below the lower nicol. If a shadow appear on
the same side of the object as the ringer is placed, the
refractive index of the object is higher than that of the
medium. If it appear on the opposite side, the refractive
index is lower than that of the medium. By means of a nicol
the two directions of vibration can be separately examined in the
manner already explained.
With monochromatic light this method gives good results.
It is usual to provide a series of liquids, the refractive indices
•of which differ by small amounts, starting from about 1*47
and extending up to 1*76, afforded by methylene iodide, or 1*83
by a solution of sulphur in methylene iodide, which is, however,
not so satisfactory. If an exact determination be required, a
mixture of two liquids is prepared, which has as nearly as possible
the same refractive index as the mineral, and the index of refractive
of this mixture is determined by the Abbe refractometer. It is
important to remember that the refractive indices of liquids
change considerably with the temperature.
If white light be employed, the phenomena are complicated
by the fact that the dispersion of the colours in liquids is usually
much greater than with solids of the same refractive index, and
a series of colour phenomena may result, which complicates the
observation. In the case of minerals with decidedly higher or
lower refractive indices than the medium there is no difficulty ;
628 J. W. EVANS ON THE DETERMINATION OF MINERALS UNDER
hut if the mineral has about the same refractive index for
blue light as the medium, but a higher refractive index for
red light, only the red light will be obscured on the same side
as the finger, so that the shadow will have a bluish tinge.
When all the refractive indices of the mineral are included
between the extreme indices of the medium, there will be
a bluish colour on the finger side and a yellowish-red one
on the opposite side ; and when the red refractive indices are
the same but the blue refractive index of the medium is greater,
there will be a red shade on the far side. The colours obtained
with particular liquids are sometimes very characteristic of
minerals, and may thus be employed for their identification.
All the particulars obtained in the investigation of the mineral
sections should be embodied in the sketch as shown in fig. 1.
The following is a brief abstract of the procedure in the detailed
examination of the optical characters of a mineral.
A. Examination of the object-image.
1. With stage in the zero position, sketch the mineral and
indicate the positions of 0°, 90°, 180° and 270° by short lines
directed inwards from the circumference (p. 601).
2. Determine the positions of edges, cleavages and other
rectilinear directions in the mineral and indicate them by dis-
continuous lines through the centre, each distinguished by its
two index readings (p. 601).
3. Determine the extinctions or directions of vibration and
show them as continuous lines through the centre with index
readings (pp. 601-604).
4. Note the absorption colours and other phenomena shown
by light vibrating in these directions (p. 604).
5. Determine the character of the directions of vibration
and the amount of relative retardation (pp. 604-613).
B. Examination of the directions-image.
6. Determine the longitudinal direction and its proximal
end, and deduce the character of the section, noting at the
same time the nature of the movement of the isogyre and any
special features in the directions-image (pp. 617-624).
All the above observations should be made, if possible, without
moving the object. If any movement be necessary, it should
be made without changing the orientation. This is best effected
bv the use of a mechanical stage.
THE MICROSCOPE BY MEANS OF THEIR OPTICAL CHARACTERS. 029
C. Observations extending to other crystals of the same
mineral and other minerals.
7. Determine the thickness of the rock-slice and calculate
the birefringence of the mineral under examination (p. 625).
8. By determining the character of other sections of the same
mineral or of those showing special features, determine that of
the mineral itself (pp. 620-624).
9. Determine the refractive index of the mineral as far as
circumstances permit (pp. 625-628).
EXPLAXATIOXS OF FIGURES.
Fig. 1. Crystal section in the position in which it is originally
drawn with index-reading zero. Most of the details
shown are subsequently added. The directions of
extinction are represented by thick lines, crystallo-
graphic directions by interrupted lines, and the posi-
tion of the cross wires only by short thick lines.
,, 2. Crystal section with the long edge and cleavage parallel
to the right and left cross wire. The index-reading
83° is shown on the right end. The directions which
originally coincided with the cross wires are shown
by short thick lines. The actual cross wires are re-
presented here and in fig. 3 by thin continuous lines.
,, 3. Crystal section with the fast ( — ) direction of vibra-
tion parallel to the slot. The quartz wedge is inserted,
and shows a black band where it exactly neutralises
the crystal. The smaller figures in the scale on the
wedge indicate hundreds, the larger thousands of
micro-millimetres of relative retardation.
,, -i. Double quartz wedge.
,, 5. Combination gypsum plate and quartz wedge.
,, 6. Mica steps.
7. Straight central isogyre showing only one branch.
The inner arrows give the directions in which the
ends of the isogyres would move if the stage were
rotated in the direction of the outer arrows.
,, 8. The same with gypsum plate inserted. The lower
colours on the farther side of the isogyre show that
the character of the section is fast ( — ).
630 J. W. EVANS ON THE DETERMINATION OF MINERALS.
Fig. 9. Pendulum movement obtained by rotation from fig. 7.
,, 10. Fan movement from fig. 7.
,, 11. Parallel movement from fig. 7.
,, 12. Fig. 7 rotated through 45°. The lower colour in the
north-east indicates the longitudinal direction and its
proximal end.
,, 13. Straight central isogyre of two branches meeting in a
black cross in a biaxial crystal.
,, 14. The same rotated through 45° with the vertices of the
isogyre still visible in the field. The gypsum plate is
inserted, and the lower colours on the concave sides
of the curves show the crystal to be slow ( + ).
,, 15. Fig. 13 rotated through 45° in a case in which the
vertices of the isogyre have disappeared. The lower
colours indicate the longitudinal direction.
,, 16. Curved central isogyre with gypsum plate. The lower
colours on the farther side of the isogyre indicate that
the section is fast ( — ).
,, 17. Section at right angles to one of the optic axes of a
biaxial mineral. The optic axial plane lies east and
west.
,, 18. The same rotated through 45° when the crystal is neutral.
,, 19. The same when the crystal is not neutral. The gypsum
plate is inserted, and the higher colours on the concave
side of the curve show that the crystal is fast ( — ).
,, 20. The same with smaller optic axial angle showing two
branches of the isogyre.
,, 21. Section at right angles to the optic axis of a uniaxial
crystal — that is to say, one in which the acute optic
axial angle is zero. The higher colours in the angles
traversed by the slot and plate show that the crystal
is fast (— ).
The directions of the arrows in figures showing isogyres in-
dicate the relations between the angular directions of the move-
ments of the ends of the isogyre and that of the rotation of the
stage, and their lengths the relative angular velocities.
Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 11, November 1915.
Jo urn. Q. M. C.
Ser. 2, Vol. XII., PI. 35.
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Magnification 63 times
Determination of Minerals.
(By permission of the Geologists' Association.)
Journ. Q. M. C.
Sim-. 2, Vol. XII., PL 36.
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Determination of Minerals.
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Ser. 2, Vol. XII, PL 37.
Determination of Minerals.
(By permission of the Geologists' Association.)
631
ON FIVE NEW SPECIES OF THE GENUS
HABROTROCHA.
By David Bryce.
{Read October 26th, 1915.)
Plates 38 and 39.
In the following paper I describe five new species of pellet-
making Rotifera, which are to be added to the already important
genus Habrotrocha. The first two, H. insignis and H. sylvestris,
may be said to belong to the central group of the genus, being
closely related to H. angusticollis (Murray), which has been
designated as type species by Woodcock.* The characteristics
of this central group consist of a relatively long and slender
head and neck, a middle body distinctly stouter, and an exceed-
ingly short foot, together with rather narrow trochal disks borne
on somewhat high pedicels usually adnate. H. insignis has
other more special characteristics, one of which has not been
seen in any other Bdelloid. The upper lip, when closely exam-
ined, is found to have a curious stiffening, apparently that it
may better support the slender pedicels under the strain of
the lashing cilia above. This stiffening is not very obvious,
but once observed is readily recognised and can be detected even
when the corona is retracted within the mouth.
A second interesting structure is the looping of the gullet in
a certain position of the body. A similar structure has been
already noted by Zelinka for Habrotrocha Leitgebii, and it is also
present in two of the other new species, viz. U. sylvestris and
H. flava. The looping of the gullet is one of several structural
modifications that are distinctly connected in their origin with
the attitude assumed by the rotifer when it is feeding. There
are some Bdelloids of the family of the Philodinidae which feed
without attempting to extend themselves, but others extend
themselves habitually to the utmost, without doubt in order to
* Woodcock, Int. Cat. Set. Lit., vol. x., 1911. Zoology, vi. p. 45.
632 DAVID BRYCE ON FIVE NEW SPECIES OF
gather food from the increased area thereby brought within
the influence of the vortices set up by the cilia of the trochal
disks. This habit of extension for the purpose of increasing the
food supply reacts in two different ways upon the structure of
the body. One of these is very apparent in such species as
Rotifer vulgaris and its nearer relatives, where the foot and the
rump segments have become so elongated that they constitute
quite a large proportion of the whole length of the animal.
In the central section of the Habrotrochae the head and neck
are lengthened to a marked extent, whilst the rump and foot
segments, and especially the latter, become or remain relatively
short and unimportant. The neck frequently becomes so
slender that the mastax is pushed backwards into the last seg-
ment of the neck when the animal is crawling, and into the
anterior segment of the trunk or central body when it is feeding.
The increasing distance from the mouth to the mastax necessi-
tates in turn a longer gullet, which is fully but not tensely
stretched out when the animal displays its corona. When the
latter is withdrawn, the inversion of the mouth reduces the
distance to the mastax, and the connecting gullet becomes slack.
In extreme cases the slackness is so great that the gullet, which
is usually a little stouter near the mastax, bends over, just above
the stouter part, towards the ventral side, and so forms a loop,
which is not straightened out until the corona is again everted.
It is very difficult to see the loop distinctly. The animal must
be observed in side view and at the moment when the neck is
fully extended, for the gullet is not truly " looped " if it straightens
out before the eversion of the corona.
In some species a further modification is seen. Not only is
the mastax shifted rearwards, but also the brain, which is nor-
mally so placed that the narrow anterior end is close to the
dorsal antenna, while the broader posterior part more or less
overlaps the mastax. In II. insignis the anterior end of the
brain is placed about one-half the brain-length behind the
antenna, and this also is best seen in lateral view. I find
that this modification of the position of the brain does not
obtain in all the slender-necked Habrotrochae, and it seems
therefore to be a character useful for the differentiation of
such species.
Habrotrocha insignis, again, is one of the few species of Bdelloid
THE GENUS HABROTROCHA. 633
Kotifera which not only can endure life in the most exposed
situations, but which even seems to prefer it. It would be
difficult in Great Britain to find mosses growing in bleaker
places than on the tops of the Scottish and Welsh mountains,
yet wherever in such elevated places mosses can be found growing
and braving the storms, this species, sheltering in the moss-tuft-;,
seems able to flourish exeeedinsiv well.
In many respects the new species Habrotrocha sylvestris is
closely allied to H. insignis, but the upper lip is not so high, and
lacks the curious stiffening so distinctive in the latter. On the
other hand H. sylvestris has a unique character of its own. In
certain Distylae (for example, D. depressa) the lower end of the
oesophagus (which seems to project into the stomach cavity)
has an incessant undulatory movement. I found a similar
movement of the oesophagus in H. sylvestris, where it has pro-
bablv some connection either with the formation of the food-
pellets or with their discharge into the stomach.
Both H. insignis and H. sylvestris are probably of near relation-
ship to H. tridens (Milne), which, however. I judge, from the
description and figure given, to be an altogether more slender
and cylindrical animal than either. I have not been able to
identify it with certainty.
The third species described, Habrotrocha pavida, is of quite a
different type, and is notable for its moderately wide corona,
and the bulging lateral margins of the mouth, which give it a
very characteristic outline when favourably seen. Although it
has been known to me for many years, it has, with one exception,
only been found in moss growing among the grass in a small
suburban garden. It is a very timid species, and will rarely
feed unless it is ensconced in a convenient ' heap ' of sand or
debris, from which it protrudes its head " at mealtimes." In
an earlier paper * I have described the manner in which the food-
pellets are moulded in the case of H. constricta (Dujardin). In
H. pavida there is a little more elaboration of the process. If a
good lateral view can be obtained while the animal is feeding,
the greater part of the oesophagus can be seen, albeit somewhat
indistinctly. The inner surface of the tube is apparently lined
with cilia, for there is an almost continuous undulatory move-
* Bryce, " Further Xotes on Macrotrachelous Callidinae," Jourri.
Quek. Micr. Club., Vol. V., Ser. II., pp. 436-155. Xo. 35, 1894.
634 DAVID BRYCE ON FIVE NEW SPECIES OF
ment carrying along the food particles towards the end farther
from the mastax. Arrived near that end, they become incor-
porated in a pellet, which is revolved at moderate speed until
it is large enough to be expelled into the wide stomach, where
its revolving motion ceases. The growth of the pellet at its
beginning could not be seen, but perhaps a minute or so after
the expulsion of one pellet there could be discerned a tiny mass
which, revolving slowly, gradually increased in bulk, the whole
process lasting from five to ten minutes if the animal continued
feeding steadily. The undulatory movement of the oesophagus
seemed to be similar to that frequently observable in the gullet,
and less violent than that of the oesophagus in //. sylvestris, and,
further, it seemed to cease if no particles of food were being passed
along, just as it does in the gullet.
Like all the foregoing species, Habrotrocha flava, sp. nov., is a
dweller in ground moss, although on one occasion I found it in
moss which had been growing on a roof, but becoming detached
had rolled into the roof gutter. It is a brightly coloured species,
for whilst the whole body in the adult is distinctly yellowish,
the colour of the stomach deepens almost to a bright rust-red.
The corona has a somewhat unusual structure which I later
describe in detail, and the many-toothed rami, the stout foot
and wide separation of the spurs make this an easily recognisable
species.
A very different habitat is characteristic of Habrotrocha longula
sp. nov., which shows a preference for mosses and algae, growing
in running water in the more mountainous districts, where it is
constantly found in company with Philodina flaviceps Bryce
and Philodinavus paradoxus (Murray), which also delight in such
situations.* This species has the same habit as H. pavida of
taking shelter in any available aggregations of sand or debris.
The stomach in adult examples is usually vividly coloured in
tints of pinkish red. Its elongate form, short foot, and peg-
like spurs, held nearly parallel, seem to show relationship to
* I have occasionally met with a form nearly related to H. longula,
perhaps identical with it, in submerged confervae or mosses growing
upon artificially made edges of town ponds and in watercress in a
country ditch, but I have not had the opportunity of comparing any
of the few examples thus found with my notes or sketches of the form
now described.
THE GENUS HABROTROCHA. 635
//. clegans (Milne), which, however, has a narrower corona and
a still shorter foot.
Habrotrocha insignis, sp. nov.
PI. 38, fig. 1.
Specific Characters. — Head and neck long, slender ; trunk
much stouter ; foot very short. Corona narrow, three-fourths of
collar width ; disks dorsally canted and separated by notch ;
pedicels rather high, slender, adnate. Upper lip undivided, rising
nearly as high as pedicels, centrally rounded, stiffened by rigid
bent rod of staple-like outline. Mastax far back ; rami with
three teeth each. Gullet long and looped. Brain remote from
antenna. Spurs short, acute cones, without or with little inter-
space.
When crawling this species bears some resemblance to Habro-
trocha angusticollis (Murray), when the latter is seen out of its
case. The skin of the long head and neck is so smooth that it
has a somewhat bright and tight appearance. That of the
trunk is finely punctate or stippled along the longitudinal skin-
folds, which are distinctly marked, the four central extending
over the preanal segment. In well-grown examples the trunk
is somewhat long and so much stouter than the neck as to give
a somewhat swollen appearance. It gradually increases in size
up to the fourth central segment, the succeeding preanal seg-
ment being nearly as large, and the anal much smaller, and so
rapidly diminishing to the end of the short three- jointed foot.
The slender rostrum has rather prominent lamellae. In front
of the antenna is seen within the head a curious structure, which
may be likened to a thin, rigid rod bent into the form of a staple,
but which may be the thickened margin of a concave plate
having that outline. No similar structure has yet been detected
in any other species. When the corona is protruded this bent
rod or plate is seen to be external on the dorsal side of the upper
lip. The points of the uprights are now directed forwards
(having pointed backwards while the corona wTas hidden), and
the closed end to the rear, about level with the anterior margin
of the base of the retracted rostrum. In dorsal view the uprights
diverge very slightly, the points reaching the anterior edge of
the upper lip on each side, not far from the centre. In lateral
636 DAVID BRYCE ON FIVE NEW SPECIES OF
view they are seen to be curved and to enclose a concave area.
Whether bent rod or plate, the structure seems to be a support
for the high upper lip, and indirectly for the slender pedicels.
The under lip is only moderately prominent, but in lateral view
the sides of the mouth seem rather high. Behind the mouth I
saw several faintly marked annular plicae. The positions of the
mastax and of the brain and the looped gullet have been des-
cribed above.
The short foot tapers rapidly and is about equal in length to
one-sixteenth of the whole body. On the dorsal surface of the
proximal joint, just behind the anus, is a strong thickening of
the hypodermic skin, conspicuous in lateral view when the animal
is extended. When feeding most of the foot is retracted within
the body, and the extremity is covered by the rump. When
the animal is crawling there is no slithering movement. The
antenna is of moderate size.
Like many of its near relatives, this species is exceedingly
timid. When it ventures to display its corona it usually adopts
very curious positions. A favourite position is attained by the
animal bending the head and neck back until the corona nearly
touches the rump, and then turning the head half round so that
the corona presents a lateral and inverted view. Poses of this
character are frequently seen among tube-dwelling species with
long, slender necks, and it would not be surprising if H. insignis
should later be found to belong to this section, although no
tube-dwelling habit has yet been observed. It is, of course,
equally possible that it may have been a tube-dwelling species
in the past.
An example isolated laid eggs of usual type, oval, smooth and
hyaline, and measuring 66 jx x 46 /x.
My largest examples measured about 290 \x in length, the
rami 15 //,, the spurs 4 to 5 $x ; the corona about 20 /x wide,
and the collar about 26 fx.
First obtained in ground moss from Baden (? Schwarzwald)
in 1894, and thereafter in moss collected by Mr. D. J. Scourfield
on Cader Idris in 1895; in moss from the top of Ben Vrachie
(Perthshire) in 1908 ; in liverwort collected by Mr. G. K.
Dunstall near Lynton (North Devon) in 1914, and in rock moss
from the summit of Snowdon (Wales), gathered by Mr. Lionel
Bennett in the same year.
THE GENUS HABROTROCHA. 637
Habrotrocha sylvestris, sp. nov.
PI. 39 fig. 2.
Specific Characters. — Head and neck slender, elongate ; trunk
much stouter. Corona narrow, disks scarcely separated, much
canted to dorsal side ; pedicels adnate, obliquely truncate,
hidden in dorsal view by upper lip, which rises in bold curve
nearly to edge of disks, and is centrally obtusely angled and
moderately deep. Gullet long, looped. Brain close to antenna.
Mastax set far back when feeding. Rami with two and three
teeth respectively. Foot short, usually hidden. Spurs short,
acute, conical, slender, divergent. Oesophagus with constant (?)
undulating movement.
I have seen only some five or six examples of this species,
which seems to be closely related to H. angusticollis. It differs
very markedly in the form of the under lip, which is not pro-
duced into a spout-like front, but simply rounded like the edge
of a cup. When feeding, a few annular wrinkles are visible on
the ventral and lateral surfaces of the head about the level of
the retracted rostrum, and to right and left of the antenna are
two minute decumbent processes. The animal crawls in a rather
leisurely fashion. On one occasion I saw a rough tube, partly
secreted, partly of entangled particles, and I have seen eggs
measuring about 70 /x x 40 ft, of normal outline, smooth and
hyaline.
I have no record of the length when extended, but estimate it
about 220 //. When feeding , the individual figured measured
about 190 fx.
Several examples were found in ground moss collected by
Mr. A. W. Sheppard in St. Leonard's Forest, Horsham, in 1909.
Another was detected in moss sent me by Mdle. Montet, of
Vevey, Switzerland, and one other in moss from the Black Forest,
Baden, which the late Mr. John Stevens, of Exeter, had received
and kindly shared with me.
Habrotrocha pavida, sp. nov.
PL 38, fig. 2.
Specific Characters. — Body gradually increasing to greatest
width near rump, thence rapidly diminishing ; foot small, of
638 DAVID BRYCE ON FIVE NEW SPECIES OF
three joints, hidden except spurs. Corona rather wider than
collar, pedicels separated by moderate sulcus. Upper lip low,
central portion slightly produced to about level of nexus between
pedicels, rounded and undivided. Sides of mouth with strong
external prominences. Rami obtusely angled, each with four
teeth. Spurs slender, acute, held nearly parallel, sometimes
slightly incurved, decurved, claw-like, bases separated by inter-
space nearly equal to spur length. Toes three, small, conical.
In adults the whole body is tinged with yellow, and some-
times the skin is slightly viscous. It usually attains its
greatest width in the hinder part of the fourth central segment,
and thence narrows rapidly to the small foot, which is so
hidden beneath the rump that even when crawling only the
spurs can be seen in dorsal view. In this it resembles Habro-
trocha elegans (Milne), but the body is generally stouter, the
increase in size rearwards more marked, and the spurs are not
peg-like. When disturbed it crawls about very actively. The
corona is wider than is usual in the genus, exceeding the width
of the collar. This is not obvious, for the lateral margins of the
mouth have each a strong rounded external prominence, which
are visible in dorsal view, and, being exactly at the level of the
collar, add to the apparent width of the latter. A similar effect
has been seen and described in Calledina angusta Bryce, and I
have also seen it in Calledina aculeata (Milne), but in these species
the prominences are angular and rather less conspicuous. The
post-oral segment has an annular thickening of the skin, rising
to small bosses at right and left of the base of the antenna. The
neck and gullet are not unusually long, and the brain is close
behind the antenna. The rami are somewhat triangular in out-
line, and have each four well-marked teeth. When feeding, the
foot and the greater part of the rump segments are usually with-
drawn or hidden beneath the trunk. The spurs are rather
slender and acute, held almost parallel, the inner side almost
straight, the outer slightly curved, somewhat decurved and
claw-like, and have their bases separated by a moderately wide
interspace ; altogether they are of an unusual and rather dis-
tinctive form.
The stomach usually contains pellets of good size. The
process of their formation has been described above.
This very distinct species seems to take up its position in
THE GENUS HABROTROCTIA. 639
the leaf axils of certain small ground mosses, and to gather
round it an accumulation of particles within which it shelters,
and possibly thus makes a tube of a most elementary description.
It produces eggs of broadly ovate form, with rather obtuse ends,
shells smooth and hyaline, measuring about 76 fj. x 51 /i.
Length, extended, about 270 // ; feeding, about 170 jx.
Eami, 20 fx. Spurs, 6 fx. Width of corona, 38 p.
Habitat. — Moss among short grass in my garden, Stoke New-
ington, and (one individual only) in tree moss from Norton's
Heath, Essex.
Habrotrocha flava, sp. now
PL 38, fig. 3.
Specific Characters. — Corona spreading, yet little wider than
collar. Pedicels high, sub-adnate. Upper lip undivided, rising
rather high to rounded tip. Neck moderately long ; gullet
looped ; mastax far back ; rami with six or seven teeth each.
Foot very short and stout ; spurs short, strongly decurved,
widely separated and diverging ; interspace very convex.
A species of moderate size with several distinctive characters.
"While apparently allied to the long-necked species of the genus,
the head and neck are less slender than is customary in that
section. The adults are frequently conspicuous from the vivid
yellowish red of the stomach and the paler tint of the remainder
of the body. The corona appears to be of unusual type. In
place of the pedicels being straight, slightly diverging or parallel
columns, they seemed to be separated at their bases, to approach
each other at half height, and thereafter to diverge ; the inner
line of each showing thus a bold curve in dorsal view. Yet they
seemed to be connected by a delicate membrane from their
bases to near the plane of the trochal disks. I could discern on
the dorsal line an unusually faint line marking, as I thought, the
•outline of a very delicate upper lip, and farther back in front of
the retracted rostrum a much stronger line moderately curved
crossing the head. The head is rather elongate when the corona
is displayed, and the mastax is then usually in the first and
occasionally in the second trunk segment. The gullet is long
.and is looped when the animal is not feeding. The anterior of
640 DAVID BRYCE ON FIVE NEW SPECIES OF
the brain is a little way behind the dorsal antenna. When
feeding, this species usually conceals the whole foot below the
rump segments. The foot has, I think, three segments, the
second somewhat disk-like and carrying two widely separated
spurs, which in dorsal view seem to be short, stout cones, but
are really only moderately short and strongly decurved. The
interspace between them is strikingly convex, and about 12 \x
wide. Two strong and broadly truncate toes were seen re-
peatedly ; a third was possibly present, but not detected. On
the post-oral segment there is a small prominence on either
side of the short antenna.
Length, 320 /*. Rami, 21 fx. Corona, 23 //. wide.
In ground moss at Mundesley and roof moss at Paston, near
Mundesley ; also in ground moss collected by Mr. G. K. Dunstall,
in Surrey.
Habrotrocha longula, sp. nov.
PI. 39, fig. 1.
Specific Characters. — Rather elongate and slender ; body
nearly cylindrical ; foot very short. Corona wider than collar ;
pedicels separated by narrow gap ; disks slightly canted to dorsal
side. Upper lip rising to moderately high, obtuse, median point.
Brain long, anterior close to antenna, posterior just overlapping
mastax. Gullet not looped. Rami somewhat triangular, longish,
each with five teeth. Spurs short, stout pointed cones, held
nearly parallel.
In searching washings of moss or algae from stones in swiftly
running streams in hilly districts or near the shores of mountain
lakes, one frequently finds this species in numbers, and marching
about with much pertinacity, though not with much speed. It
attracts attention by its bright colour, the alimentary tract being
frequently of a vivid orange-red to pink-red tint, and the re-
mainder of the body of a much paler shade. If left undisturbed,
the various individuals take shelter after a time in convenient
,l heaps " of particles, or of " floccose," and will presently com-
mence to feed and so settle down to satisfy their healthy appe-
tites. I have sometimes been able to see a rudimentary secre-
tion of a case, and have no doubt that a certain amount of
THE GENUS HABROTROCHA. 641
viscous fluid is produced in some such way to bind together
the sheltering particles or fibres. In several respects this rotifer
has marked affinity to Habrotrocha elegans (Milne), which has a
similar shelter-taking habit. But the head and the corona are
larger in proportion, the foot is less hidden beneath the rump ;
the spurs are stouter, though rather like in style and pose, and
the teeth of the rami are five in number.
When feeding, the animal usually bends the anterior part of
the body, protruded from the " shelter," to one side or the
other, or even backwards, but I have not seen any extravagant
contortions of the neck. It lives fairly well in small troughs, and
even in small cells I have kept it for over two months.
The form and proportions of the upper lip as shown in
fig. la (PI. 39) seem rather distinctive. The lateral margins of
the mouth are slightly prominent, but less so than in //. pavida.
The underlip is slightly produced and spout-like. In one case I
saw the pellets being formed at a distance of about 15 /x behind
the rami, and the oesophagus seemed to be from 20 to 25 /x long.
The pellets made are small to moderate in size. On several
occasions the rather long and normally placed brain seemed to
me to show reddish blotches as of suffused pigment, but I failed
to detect any definite eye-spots, such as are so distinct in the
cognate Habrotrocha collaris Ehrbg. When apparently fully
protruded the dorsal antenna measured about 19 /x. In the
feeding position it is inclined forwards, almost resting against
the retracted rostrum, but towards the tip it is slightly recurved.
The terminal foot joint is stout at the base, but tapers rapidly,
and on two occasions I have seen three short, stout, truncate
toes protruded.
The eggs are laid within the " shelter " and are of oval outline,
smooth and hyaline ; measuring about 57-60 /x in longest, and
39-40 /x in shortest diameter.
Length, 300-350 /x. Spurs, 6 /x. Width of corona, 35-38 p.
From rock moss from summit of Ben Vrackie, Perthshire
(1907). In moss close to a waterfall near Milford, South Wales,
collected by Mr. G. K. Dunstall. In ncrustation of stones from.
Untersee, and in mosses from Mittersee, Lunz, Austria, sent me
by Dr. von Brehm, of the Lunz Biological Station (1911-13).
Jourx. Q. M. C, Series II.— No. 77. 36
642 david bryce on new species of the genus tiabrotrocha.
Description of Plates 38 and 39.
Plate 38.
Fig. 1. Habrotrocha insignis, sp. no v., dorsal view, feeding
position, x 590.
,, la. Head and neck, corona displayed, in lateral view, x 590.
,, 2. Habrotrocha pavida, sp. nov., dorsal view, feeding position.
x 590.
,, 2a. Same, in lateral view, x 590.
„ 26. Rami, x 1,180.
,, 2c. Foot, showing spurs and toes, x 590.
,, 3. Habrotrocha flava, sp. nov., dorsal view, feeding position.
X590.
,, 3a. Part of foot, showing spurs. X 590.
Plate 39.
Fig. 1. Habrotrocha longula, sp. nov., dorsal view, extended.
X590.
,, la. Dorsal view, feeding position, x 590.
,, 16. Head and neck, corona displayed, in lateral view, x 590.
,, lc. Rami, x 1,180.
,, 2. Habrotrocha sylvestris, sp. nov., dorsal view, feeding
position, x 590.
,, 2a. Head and neck, corona displayed, in lateral view, x 650.
„ 26. Rami, x 1,180.
,, 2c. Spurs, x 590.
Journ. QuekeU Microscopical Club, Her. 2, Vol. XII., No. 77, November L915.
Journ. Q. M. C.
Ser. 2, Vol. XEI., PL 38.
y~
1 4
■ ■ ■ Yjf ■
> './ fMM fit ;
D. Bkyce, del. ad nai.
lev
New Species of Habrotrocha.
Jo urn. Q. M. C.
Ser. 2. Vol. XII., PI. 39.
4 /
%.
i \
1
Ac
D. Bryce, A/, a.i nat.
New Species oe Habrotrocha.
643
NOTICES OF BOOKS.
The British Freshwater Rhizopoda and Heliozoa. By
James Cash and George Herbert Wailes, F.L.S., assisted by
John Hopkinson, F.L.S., F.Z.S. 8J x 5|. Vol. I. The Rhizo-
poda, Pt. I. x + 150 + 32 pages, 16 plates. 8vo. 1905.
Vol. II. The Rhizopoda, Pt. II., xviii + 168 + 32 pages, 16
plates and frontispiece. 8vo. 1909. Vol. III. The Rhizopoda,
Pt. III., xxiv + 156 -f- 50 pages, 25 plates and frontispiece.
8vo. 1915. The Ray Society. Price £1 17s. 6d. net.
It is with great pleasure we draw attention to the publication of
the third volume of the above work ; this completes the section
devoted to the British Freshwater Rhizopoda with the exception
of about forty species recorded since 1909, the date when the
second volume was issued. It is intended to include descriptions
and figures of these species in a fourth and final volume which will
also include the British Heliozoa.
From a short history of this work at the commencement of the
second volume we learn that Mr. Cash passed away early in 1909
and did not see the completion of that volume. We must con-
gratulate the Secretary of the Ray Society in securing the services
of such a competent worker as Mr. G. H. Wailes to complete the
work left unfinished by its original author, the third volume
which has just been published being by him. Mr. Hopkinson has
provided a short memoir of James Cash. Before studying the
Rhizopoda he had devoted considerable attention to Bryology,
and his collection of drawings and specimens has been presented
to the Manchester Museum. When he first turned his attention
from the mosses to the rhizopods we do not know, but in 1891 he
read a paper before the Manchester Microscopical Society giving
the results of his investigations of the Rhizopoda of the Manchester
area in the same year. This paper added several species to the
British list, and seems to have revived an interest in the fauna
of these microscopic creatures. These volumes show how far
that interest has been carried and cannot fail to be an aid and
incentive to the microscopist in making further records of the
644 NOTICES OF BOOKS.
rhizopodal fauna of the districts in which they reside. In this
connection it may be remarked that with the exception of Loch
Ness not one of the larger British lakes has been investigated as
to the rhizopodal fauna of either the plankton or deposits, a
large and unworked field awaiting investigation. To the micro-
scopist desirous of working in this interesting department of
micro-fauna we may draw attention to two papers recently
published: (1) Dr. Eugene Penard, "Collection and Preser-
vation of Freshwater Rhizopoda," Journ. Q.M.C., Vol. X.,
pp. 107-116; (2) G. H. Wailes, "Notes on the Structure of
Tests of Freshwater Rhizopoda," Journ. R.M.S., April, 1915,
pp. 105-116, 2 plates.
In the third volume of The British Freshwater Rhizopoda there
are twenty-five plates from drawings made by Mr. Wailes, a
larger number than in either of »the previous volumes. Of
these eight are coloured, and their beauty cannot be too highly
praised. Through the courtesy of the Secretary and Council of
the Ray Society we are able to present our members with a copy
of Plate XLIV. The uncoloured plates are in collotype, and
are, we think, a great improvement on the half-tone reproductions
which appeared in the previous volumes. The frontispiece to this
volume is a particularly interesting one, being reproductions
in» collotype of photo-micrographs from preparations made by
Dr. Eugene Penard, of Geneva.
In the case of all three volumes Mr. John Hopkinson has been
responsible for the synonymic references, and the amount of labour
and critical insight that he has devoted to this share of the work
can only be fully realised by one who has done similar work.
The arrangement of the references in this volume is an improve-
ment on that of the two previous volumes.
Description of Plate 40.*
Paulinclla chromatophora Lauterborn. Figs. 1,2: Side view
and transverse section of an active individual, x 1,500. Fig. 3 :
Process of division, x 1,500. Fig. 4 : Nucleus, x 2,000. All
after Lauterborn .
P. chromatophora var. pulchella (G. S. West) Wailes. Figs. 5, 6 :
* British Freshwater Rhizopoda, Vol. III., PI. XLIV.
Journ. Q. M. C.
Ser. 2, Vol. XII., PL 40,
y
8
10
w
13
11
12
Rhizopoda.
NOTICES OF BOOKS.
645
Oral and side views, after West, x 750. P. chromatofhora
Lauterborn. Figs. 7. 8 : Side and oral views, after Brown.
x 1,200.
Lecythmm hyalinum Hertwig and Lesser. Fig. 9: Solitary
active individual. Fig. 10: Appearance of same when deprived
of air. x 500. L. granulatum (Schulze) Hopkins. Fig. 11 :
Individual distended by ingested diatoms; from a specimen
stained and mounted by Dr. Penard. x 300.
Diplophrys archcri Barker. Fig. 12 : Active solitary individual.
.Fig. 13: Process of tetrad division, after Hertwig and Lesser,
x 1,000. ' ,
646
THE CLUB CABINET.
The following Slides have been added to the Cabinet since
October 1914 :
Echinodermata.
Presented by C. J. H. Sidwell.
N. 32. Spicules of Plexaura flexuosa.
Rotifera.
Presented by C. F. Rousselet.
Series 21. Typical genera.
Anuraea aculeata (Ehrenberg).
Asplanchna Brightwelli (Gosse), $ and $.
Brachionus pala (Ehrenberg).
Cathypna luna (Ehrenberg).
Euchlanis hyalina (Leydig).
Hydatina senta (Ehrenberg), <$ and $.
Lacinularia socialis (Ehrenberg).
Metopidia lepadella (Ehrenberg).
Notholca scapha (Gosse).
Polyarthra platyptera (Ehrenberg).
Rhinops nitrea (Hudson).
Synchaeta tremula (Ehrenberg).
Insecta.
Presented by the late Prof. E. A. Minchin.
Series 22. Anatomy of the Rat Flea (Ceratophyllus fasciatus).
Twenty-four Slides of dissections of the nervous, genital and
salivary systems, etc., with descriptive text and plates.
THE CLUB CABINET. 647
Mycetozoa.
Presented by C. H. Huish.
C.A. 1. Arcyria cinerea (= albida).
2. Arcyria jerruginea.
3. Badhamia rubiginosa, var. dictyospora.
4. Ceratiomyxa jructiculosa (= mucida).
5. Diachoea leucopoda (= elegans).
6. Dictydium cancellatum (= umbilicatum) .
7. Didymium dubium.
8. Didymium melanospermum (= jarinaceum).
9. Lamproderma columbinum.
10. Physarum contextum.
11. Physarum viride.
15. Trichia botrytis, var. latcritia.
Musci.
Presented by G. T. Harris.
Classification from Dixon's Student's Handbook of BritishMosses,
second edition.
D.A. 6. Amblystegium serpens.
7. Amblystegium varium.
8. Barbula lurida.
9. Barbula rubella.
10. Barbula tophacea, peristome.
11. Barbula unguiculata.
12. Barbula unguiculata, peristome.
13. Brachythecium populeum.
14. Brachythecium rutabulum, var. longisetum.
15. Brachythecium rutabulum, peristome (opaque).
16. Brachythecium rutabulum, peristome.
17. Brachythecium rutabulum, leaves of type.
18. Brachythecium velutinum.
20. Bryum atro-purpureum, var. gracilentum.
21. Bryum capillare, peristome.
23. Bryum pollens, " female flower.'
24. Campylopus flexuosus.
25. Catharinea undulata, peristome.
26. Ceratodon purpureus.
)5
648 THE CLUB CABINET.
D.A. 27. Cryphaea heteromalla, leaves.
28. Cryphaea heteromalla, peristome (opaque).
29. Dicranella heteromalla.
30. Dicranella rufescens.
31. Dicranella varia.
32. Dicranum majus, leaves to show pores.
33. Dicranum scoparium, peristome (opaque).
34. Dicranum scoparium, peristome.
35. Eurhynchium confertum.
36. Eurhynchium myosuroides.
37. Eurhynchium myosuroides, " female flower."
38. Eurhynchium pumilum.
39. Eurhynchium Swartzii.
40. Fissidens algarvicus.
41. Fissidens bryoides.
42. Fissidens bryoides, forma inconstans.
43. Fissidens Curnowii.
44. Fissidens exilis.
45. Fissidens incurvus, var. tamarindifolius.
47. Fissidens rivularis.
48. Fissidens taxifolius.
49. Fissidens viridulus.
50. Funaria fascicularis.
51. Funaria hygrometrica , peristome.
52. Grimmia apocarpa.
53. Grimmia apocarpa, peristome.
54. Grimmia pulvinata.
55. Hedwigia ciliata, leaves.
56. Hylocomium squarrosum, peristome.
57. Hypnum cupressi forme, type.
58. Hypnum cupressiforme, leaves of type.
59. Hypnum cupressiforme, " male flower."
60. Hypnum cupressiforme, var. filiforme.
61. Hypnum cupressiforme, var. resupinatum.
62. Leucobryum glaucum, leaves.
63. Neckera pumila.
64. Neckera pumila, archegonia.
65. Orthotrichum afflne, leaves and " female flower."
66. Orthotrichum affine, to show superficial stomata.
67. Orthotrichum affine, peristome (opaque).
THE CLUB CABINET. 649
DA. 68. Orthotrichum diaphanum, to show "immersed" stomata.
69. Orthotrichum diaphanum, peristome (opaque).
70. Orthotrichum Lyellii, leaves bearing gemmae.
71. Plagiothecium elegans, showing flagellae.
72. Pleuridium subulatum.
73. Polytrichum formosum, sections of leaves to show
lamellae.
74. Pottia lanceolata.
75. Pottia truncatula.
76. Pterygophyllum lucens.
77. Bhacomitrium lanuginosum.
78. Sphagnum acutifolium, branches.
79. Sphagnum acutijolium, to show '" retort " cells.
80. Sphagnum cymbifolium, stem to show spiral vessels.
81. Sphagnum rigidum, var. compaction.
82. Tortula aloides.
83. Tortula laevipila.
84. Ulota phyllantha, leaves.
85. Weber a carnea.
Plant Structure (Cellular).
Presented by C. J. H. Sidwell.
D.B.* 29. Leaf of Holly Fern.
30. Leaf of Hymenophyllum Tunbridgense.
E. 36. Leaf of Althaea rosea : Hollyhock.
E.A. 59. Leaf of Pinguicula vulgaris : Bntterwort.
Seeds.
Presented by C. J. H. Sidwell.
G. 48. Orthocarpus sp.
49. Pterospora andromedea.
2. Spergula minor.
Fossil Botany.
Purchased. J. Lomax, preparer. 3 in. by 2 in. slips.
The figures in ( ) refer to illustrations in Dr. D. H. Scott's
Studies in Fossil Botany, 2nd edition (copy in Q.M.C. Library;.
650 THE CLUB CABINET.
Localities : all preparations from Shore, Littleborough, Lanes.,
unless otherwise indicated.
Y.C. 1. Tr. sec. of a large stem of Oalamites.
2. (A) Tr. sec. of stem of Calamites, with portion of
cortex (figs. 4 and 5) ; (B) portion of a cone of
Calamostachys Binneyana ; (C) a root of Calamites.
3. (AA) Tr. sees, of stems of Calamites ; (B) tr. sec. of
small rootlet, probably of Amyelon ; (CC) tr. sees.
of Amyelon radicans (? the root of one of the Cor-
daiteae) ; (D) leaves of Cordaites ; (E) megasporangia
containing megaspores.
4. (AAA) Tr. sees, of Astromyelon (? the root of a
Calamites) ; (B) portion of a cone of Calamostachys
Binneyana.
5. (A) Tr. sec. of a splendid cone of Calamostachys Bin-
neyana, with sporangia full of spores (fig. 18) ; (BB)
tr. and long, sections leaves of Calamites (fig. 14) ;
(CC) leaves of Sigillariopsis ; (D) seed of Physo-
stoma elegans. Locality : Halifax Hard Bed, Hud-
dersfield.
6. Long. sec. cone of Calamostachys Binneyana (fig. 17).
Locality : Halifax Hard Bed, Huddersfield.
7. Tr. sec. stem of Sphenophyllum plurifoliatum (fig. 38).
8. Long. sec. cone of Sphenophyllum Daivsoni, showing
bracts, etc., at A, and sporangia containing spores at
B (figs. 42-44).
9. Tr. sec. stem of Lepidodendron selaginoides. Locality :
Halifax Hard Bed, Huddersfield.
10. (A) Tr. sec. stem of Lepidodendron selaginoides (figs.
59 and 60) ; (B) tr. sec. stem of Lepidodendron macro-
phyllum. Locality : Cloughfoot, Dulesgate, near
Todmorden.
11. Tr. sec. stem of Lepidodendron juliginosum.
12. Tr. sec. stem of Lepidodendron Harcourtii.
13. Tr. sec. stem of Lepidodendron Harcourtii, showing at
(A) the stele with primary and secondary xylem,
(B) inner cortex, (C) outer cortex, and (D) leaf-
bases (fig. 56).
14. Tang. sec. leaf-bases of (stem of Lepidodendron Har-
THE CLUB CABINET. 651
courtii (Lepidophloios). In many of the leaf-bases
the vascular bundle, parichnos strands and ligule
are seen (fig. 62).
Y.C. 15. (A and B) Tr. sees, stems of Bothrodendron mundum ;
(C) tr. sec. of a similar, but much smaller, stem.
16. Tr. sec. cone of Lepidostrobus oldhamius with micro-
spores.
17. Tr. sec. cone of Lepidostrobus oldhamius. This cone
does not contain any spores, but the axis and laminae
are well shown.
18. Tr. sec. portion of Stigmaria ficoides, showing at A the
zone of wood, with cortex and rootlet-bases at B
and C (figs. 98 and 100).
19. Tang. sec. Stigmaria ficoides through outer cortex,
cutting rootlets transversely (fig. 97).
20. Tang. sec. Stigmaria ficoides through zone of wood (fig. 99).
21. Radial sec. Stigmaria ficoides.
22. Tr. sec. Stigmaria sp., showing zone of wood at A, and
cortex with rootlet-bases at B.
23. Tr. sec. stem of Etapteris Laceattei.
24. Tr. sec. stem of Metaclepsydropsis duplex. Locality :
Pettycur, Burntisland, Fife.
25. Tr. sees, stems of Botryopteris cylindrica, the one at B
being cut at junction with petiole. Locality : Hali-
fax Hard Bed, Huddersfield.
26. Tr. sec. stem of Zygopteris bibractensis (fig. 118).
27. Tr. sees, stems and petioles of Stauropteris oldhamia
(figs. 126-128).
28. Tr. sec. stem of Lyginodendron oldhamium (fig. 129).
29. Tang. sec. stem of Lyginodendron oldhamium, rootlets
being given off at A (figs. 138 and 142).
30. Radial sees, stem of Lyginodendron oldhamium, rootlets
being given off at A (figs. 138 and 142).
31. (A) Tr. sec. young stem of Lyginodendron ; (BB) leaf-
rachis ; (C) root. Locality : Dulesgate, near Tod-
morden.
32. (A) Tr. sec. leaf-rachis of Lyginodendron oldhamium ;
(B) tr. sec. young stem ; (CC) tr. sees, of roots
(figs. 139, 141 and 145). Locality, Dulesgate, near
Todmorden.
652 THE CLUB CABINET.
Y.C. 33. (A) A practically perfect long. sec. seed of Physostoma
elegans, passing through the micropyle, and show-
ing pollen-chamber containing pollen-grains ; (BB)
synangia of Telangium Scottii, the microsporangia
of Lyginodendron.
34. (A) Tr. sec. through the centre of a seed of Physostoma
elegans ; (B) tr. sec. of a Fern stem.
35. Tr. sees, steins of Heterangium Grievii (fig. 154). Lo-
cality : Pettvcur, Burntisland, Fife.
36. Tr. sec. stem of Cordaites (Mesoxylon) (fig. 189).
37. (A) Tr. sec. portion of stem of Mesoxylon multirame;
(B) root of Lyginodendron.
38. Tr. sees. Amyelon radicans (? the root of one of the
Cordaiteae) (fig. 191).
39. Splendid tr. sec. of a leaf of Cordaites (fig. 192).
40. Three sections of seeds of 31 it ros per mum compression.
653
PROCEEDINGS
OF THE
QUEKETT MICROSCOPICAL CLUB.
At the 506th Ordinary Meeting of the Club, held on March 23rd,
Vice-President D. J. Scourfield, F.Z.S., F.R.M.S., in the chair,
the minutes of the meeting held on February 23rd were read and
confirmed.
Messrs. Joseph Longmore and Joseph Lovelace Ribbons were
balloted for and duly elected members of the Club.
It was announced that ninety slides had been added to the
Cabinet of microscopic objects. Fourteen of these were pre-
sented by Prof. E. A. Minchin, in illustration of his paper read
to the tlub recently on " Some Details in the Anatomy of the
Rat-flea," and were in addition to those given on that occasion,
and seventy- two were presented by Mr. G. T. Harris, illustrating
his paper on Bryological Work.
At the request of the Chairman, Mr. C. D. Soar, F.L.S.,
F.R.M.S., then read a resume of a paper by Mr. Williamson and
himself, on the " British Hydracarina, genus Lebertia." Mr.
Soar said the genus Lebertia has been rather neglected. It
is certainly a difficult group. The species appeared to run
into one another so closelv that identification was rendered
very uncertain. However, Dr. Sig Thor, of Norway, at last
took this genus in hand. He divided it into sub-genera,
and went one by one through every species that had been re-
corded, publishing altogether in the Zoologischer Anzeiger over
thirty papers on this genus alone. Finding the way thus pre-
pared for us, Mr. Williamson and myself have worked out the
material which we had been collecting together for some years,
and the paper to-night is the result. In the posthumous memoir,
of Leberts, published in 1879, he describes and figures a
Hydracarid, which he considered new on account of the form
of the genital area. This mite he named Pachygaster tau-
insignitus. He explains the specific name by referring to the
654: PROCEEDINGS OF THE
resemblance which the light dorsal marking bore to the Greek
letter tau. The generic name was altered to Lebertia (after
Leberts) by Neuman, in 1880. Sig Thor has now divided the
genus into five sub-genera. These are as follows : 1, Lebertia;
2, Pilolebertia ; 3, Mixolebertia ; 4, Pseudolebertia ; 5, Hexa-
lebertia. Three of the type species have been found in the
British area. The type species L. tau-insignitus at present has
only been found in the Lake of Geneva. But, being the type, we
have thought it right to include a description for comparison.
We have about ten species for the British area. One species,
Lebertia trisetica (Sig Thor), sub-genus Hexalebertia, was found
in Surrey in 1896. It was sent to Sig Thor, who named it in
1900 ; two specimens were taken at the time, but it has never
been recorded since. Several of the ten species have already
been recorded, but never fully described in Britain. *
Mr. J. W. Gordon exhibited and described an objective of the
same type as that described by Mr. E. M. Nelson in the last
number of the Journal of the Club, as being the latest produc-
tion of Messrs. Zeiss. Mr. Gordon explained that his lens — a
1/2-in. dry lens, fitted with a front carrying an oil-immersion lens,
had been constructed for him by Messrs. Beck so far back as
July 1909, that he has had it in use ever since, had shown it to
various persons, and that the lens had been described in the
catalogue of the Optical Convention of 1912. The following is
the description which appeared there : ' The use of oil-immer-
sion has hitherto been confined to objectives of the 1 /8th- in. and
l/12th-in. class under an impression, which proves to be mistaken,
that oil-immersion secures no particular advantages when
applied to objectives of lower power. The model is a 1/2- in. dry
lens fitted with a supplementary lens of rather less than hemi-
spherical angle, mounted so that the centre of the sphere lies
in the object. The spherical surface, therefore, produces no
refraction, and its addition to the optical system involves no
change in the correction of an objective adjusted for viewing
an uncovered object. The abolition of the top surface of the
cover-glass, by oiling on the supplementary front lens produces
an increase of 50 per cent, in magnifying power, and a com-
mensurate increase in light-gathering power. The catoptric
haze produced by internal reflection from the front face of the
permanent front lens sinks into comparative insignificance, and
QUEKETT MICROSCOPICAL CLUB. 655
a 1/2-in. dry lens is converted into a l/3rd-in. immersion system
of much improved denning power."
Mr. G. T. Harris, of Sidmouth, formerly a member of the
Club, had presented to the Cabinet 72 micro, preparations of
various mosses. He accompanied them with a paper on " Micro-
scopical Methods in Bryological Work," which was read by
Mr. F. J. Perks. It was pointed out that mosses did not appeal
very strongly to microseopists per se, as the work to be done
with them is mostly systematic, and they yield but few " dis-
play " objects. The earlier bryologists relied mainly upon
herbarium sheets for the preservation of their specimens and
for identification purposes — a plan sufficient at a time when the
division of the group into species, sub-species and varieties was
not carried out to the extent it is now. Thirty years ago specific
distinctions were largely dependent upon general habit and the
presence or absence of the so-called " nerve " and the nature of
the leaf margin. But no bryologist of the present day would
care to decide upon specific names without microscopic assist-
ance. The impossibility of securing the perfect cleanliness so
desirable in microscopical mounts with moss specimens was
pointed out, the plants growing usually in mud, or dirty situa-
tions, and, owing to their fragile constitution, not bearing any
cleaning process without damage. Probably most bryologists
relied on glycerine jelly for mounting. Some years ago Mr.
Harris prepared a considerable collection of Hypnaceae in this
medium, but in about twelve months found the whole of them
so deteriorated as to be of no value. As in other instances the
result had been successful, he concluded the difficulty arose
from avoidable causes. In his paper he gave various precau-
tions that should be observed in using glycerine jelly. Farrant's
medium probably comes next to glycerine jelly in usefulness ;
it is very convenient to use, and, of course, allows of great delibera-
tion in arranging the object. For peristomes, which require
to be examined by transmitted light, it is excellent. Other
mediums having various advantages were then referred to,
particularly two, having copper acetate in their composition, .
one with glycerine and the other with potassium acetate ; for-
malin was also noticed. Cases in which difficulty arose owing
to the dark colour and want of transparency of the leaves, and
where manipulation was not easy owing to structure, were noted,
G56 PROCEEDINGS OF THE
and hints given for overcoming the troubles. The treatment
for satisfactorily displaying the capsule, with its peristome >
was entered upon at some length, and a reference made to the
section- cutting required, in order to render evident the com-
ponent cells of the stem and leaves. Finally the necessity for a
collection of slides as an assistance to identification was insisted
upon in the following paragraph : " Fifty years ago English
bryologists considered themselves well served with ten species
of Sphagna, the separation of which was no great strain on one's
mental powers. At the present time it is useless to touch the
group unless you are prepared to distinguish between at least
forty species, with an average of four varieties each. Of
Sphagnum acuti folium alone, Warnstorf describes sixty varieties.
It will be seen from this how valuable an authenticated collec-
tion of slides would be to the bewildered student." Dixon's
Student's Handbook of British Mosses was recommended as a
handbook to any one taking up the study of the group.
The paper was most valuable from a practical point of view,,
and would no doubt have led to an interesting and useful dis-
cussion ; but, unfortunately, owing to the lateness of the hour,
this was altogether impossible.
Votes of thanks to the donors of the slides added to the
Cabinet, and to the authors of the interesting communications
brought before the meeting, were proposed from the chair, and
carried unanimously, with great heartiness.
At the 507th Ordinary Meeting of the Club, held on April 27th,
the Hon. Treasurer (Mr. F. J. Perks) in the chair, the minutes of
the meeting held on March 23rd were read and confirmed.
Messrs. William Williamson, Roy Gerald Evans, John Richard
Duncanson, Walter Lauwers and the Rev. S. Rennie Craig
were balloted for and duly elected members of the Club.
A hearty vote of thanks was returned to Dr. E. J. Spitta for
a presentation of lantern slides of historical interest to the Club,
which had been previously exhibited to the members at the
500th meeting. The lantern slides in question were placed
upon the table for the inspection of the members. The members
also thanked Mr. C. Huish for presenting to the Club one dozen
slides of Mycetozoa. Amongst the additions to the Cabinet it
QDEKETT MICROSCOPICAL CLUB. 657
was mentioned that 40 slides illustrative of Palaeozoic Botany
had been purchased.
Mr. Ainslie, R.N., then introduced the following paper, en-
titled k" An Addition to an Objective " : Few microscopists
who have made much use of high-power dry objectives have
failed to realise the connection between the tube-length and the
thickness of the cover-glass if good definition is to be obtained.
This is, indeed, mentioned in the textbooks, but not, as a rule,
at very great length. Little is said, for instance, as to the
amount of alteration required in any given case. The sensitive-
ness of objectives varies enormously ; to a certain extent with
the formula on which the objective is constructed, but more
especially with the power. As an example, a 1/2-in. of high aper-
ture, such as the Holos or the Zeiss Apochromat, requires
a change of one or two millimetres only in the tube-length to
compensate for a change of 0*01 mm. in the thickness of the
cover-glass ; for l/6th, the figure is from 9 to 13, while for a
1/8 th, such as the Leitz No. 7, the figure is as much as 20 or 21.
Water-immersions are also subject to this sensitiveness, though
to a smaller extent, the figure in the case of a Zeiss " G " being
9'2. This feature is more important than is often realised, and
the difficulty caused thereby is enhanced by the extremely small
range of draw-tube in the average Continental stand, and un-
fortunately, in many stands of English make. The present
paper is an attempt to find a way out of the difficulty, and the
device suggested should be useful when the range of draw-tube is
insufficient, especially when the higher powers are in use. Many
years ago the celebrated Van Heurck used what he called a
"transformer" as a means of making a long- tube objective
work on a short tube, and vice versa. This consisted of a con-
vex or concave lens of low power, fitted above the objective,
which, it will be readily understood, affords a means of altering
the actual plane in which the image is formed (without affecting
the action of the objective), should it happen that the cover-
glass is of such thickness to require, for satisfactory definition,
a tube-length which would bring the image beyond the limits
of the draw- tube. With the high-power dry objectives in
common use, such as the average l/6th, the power of the addi-
tional lens required to effect the compensation for a considerable
change of cover- thickness is not excessive ; a pair of lenses,
Jourx. Q. M. C, Series II. — No. 77. 37
658 PROCEEDINGS OF THE
convex and concave, of about 3 diopters power, or about 13 in.
focus, will suffice to correct for a very considerable range of
cover- thickness ; but with higher powers, such as a l/8th, the
amount of correction which can be got in this way is a good
deal less. This might be expected, from their greater sensitive-
ness to cover-thickness. As an example of what can be done
with an objective not too high in power, it may be said that a
Watson l/6th, of N.A. 0'74, which is normally corrected for a
cover 0'18 mm. thick, and a tube-length of 200 mm., can be
made to work well through a cover-glass as much as 0"50 mm. in
thickness, if a concave lens of —8 diopters be placed behind it,
while with a convex lens of the same or somewhat lower power
it will work well on an uncovered object ; and most other objec-
tives of this power will do as well. I have so far only experi-
mented with simple lenses ; but the chromatic and spherical
corrections of the objective are not perceptibly affected, unless
the power of the additional lens is as much as 10 diopters, and
even then the effect is not serious, and is not appreciable at the
centre of the field. The magnifying power of the objective is
somewhat reduced by the convex lens, as well as the N.A.,
while with the concave lens the effect is the opposite ; but the
change is not great if the additional lens is placed as near to
the back lens of the objective as possible, though it does very
well in practice to place it behind the objective mount. There
is yet another use to which this additional lens may be put,
which, so far as I know, has not been previously described. If
for the oil in which an oil-immersion objective is immersed we
substitute water, the effect is just the same in kind as that of a
reduction in cover-thickness, though greater in degree ; and it
has been found possible to convert an oil-immersion into a
very good water-immersion by merely fitting behind it a convex
lens of suitable power. The power of the convex lens cannot
be predicted, but must be determined by trial for each objective.
It is easier to effect the conversion in the case of an oil-immer-
sion of moderate power, such as l/10th, than in the case of a
1/1 2th or higher power, though a 1/1 2th can be dealt with very
satisfactorily if its working distance is not too small. A Watson
tl Parachromatic ' l/12th, for example, requires a convex lens
of 10 diopters. It is important, in the case of a lens of this
power, to place the additional lens as near as possible to the
QUEKETT MICROSCOPICAL CLUB. 659
back lens of the objective ; this minimises the unavoidable loss
of working distance. The additional lens may very conveniently
be fitted to the " funnel stop ' commonly supplied with oil-
immersions to reduce the aperture for dark-ground illumination.
With an oil-immersion thus converted to a water-immersion, it
is useless to expect that the whole aperture will be available ;
the corrections of the objective are far too much upset for that ;
but if the additional lens is made of such diameter as to
reduce the N.A. to about 1*1, and if an illuminating cone not
exceeding N.A. 0'75 or 0*8 be employed, the performance is
in all the cases tried quite up to the standard of the ordinary
water-immersion and better than some. It should not be
forgotten that, the substitution of water for oil renders the
objective sensitive to changes of cover-thickness, and the tube-
length will have to be carefully adjusted to compensate for this.
It is hoped that this method of converting an oil-immersion
into a water-immersion may be found of use, especially to
those who occasionally require to use a water-immersion for
work on living specimens, or in other work for which an oil-
immersion would be inconvenient.
Objects were exhibited under microscopes kindly lent by
Messrs. H. F. Angus & Co., and by Messrs. W. Watson &
Son, to illustrate the paper ; these were :
1. A specimen of polished steel, with a Watson 4 mm. apo-
chromatic, N.A. 0'85, a convex lens of 6 diopters being used
to correct for the absence of a cover-glass. (Magnifying power,
340 diameters.)
2. Bacillus typhosus, showing flagella, with a Watson l/6th,
N.A. 0'74, an extra cover being introduced to bring the total
thickness up to 0'50 mm. and a concave lens of —8 diopters being
introduced. (510 diameters.)
3. Tubercle bacillus, with a Watson l/12th oil-immersion,
N.A. 1*3 working with a water-immersion, a convex lens of
-j-10 diopters being introduced to effect the conversion. (940
diameters.)
The Hon. Secretary (Mr. F. Burton) then read '; Notes on a
Diatom Structure;' by Mr. A. A. C. Eliot Merlin, F.R.M.S.
The author drew attention to a very beautiful form of tertiary
structure he recently found on a variety of Aulacodiscus comberi
from Oarnaru. The valve is on a styrax type slide of 230 forms
660 PROCEEDINGS OF THE
from that locality, and is covered with a network of dark, well-
defined secondaries, except on the parts occupied by the large
primaries. Each of the dark secondaries splits up into three or
four parts by a bright cross-bar arrangement. This structure
requires a good oil-immersion objective and a very considerable
magnification to render it readily discernible.
A photograph of the above was exhibited, and Mr. E. M.
Nelson, F.R.M.S., confirmed the presence of this structure from
a specimen in his cabinet. Mr. Merlin also exhibited two other
photographs of a diatom. Mr. Nelson had written him that he
had discovered that Coscinodiscus simbirsJiii, which, with ordinary
transmitted light, resembles Coscinodiscus asteromphalus , when
examined with a dark ground and a rather small stop looks like
Actinoptychus splendens. This led him to search for the diatom
specified, and although this could not be found, he found one
which, with a dark-ground illumination, revealed a beautiful
radiating structure, somewhat resembling a Heliopelta, which
was not observable by transmitted light. On the photographs
of this specimen being examined it was identified by Mr. Mor-
land as Janischia antiqua, Grunow. Mr. Merlin further pointed
out that, although diatom-dotting has influenced the develop-
ment of the microscope towards perfection more than anything
else, he is unable to find out particulars of its introduction. Mr.
Nelson sent an extract from Messrs. Sollitt and Harrison's
paper, read before the British Association at Hull in 1853 :
" We in Hull first discovered the delicate markings on their
silicious coverings, and pointed them out to others as the proper
tests for lenses. The first of the Diatomaceae on which the
lines were seen was the Navicula hippocampus of Ehrenberg —
this was early in 1841, when specimens were sent to the
Microscopical Society of London — also to Mr. Smith, Mr.
Ross, Messrs. Powell & Lealand, M. Nachet in Paris, and Pro-
fessor Baile}7 in America, all of whom at once saw the excellency
of these objects as tests for the microscope."
At the 508th Ordinary Meeting of the Club, held on Tuesday,
May 25th, the Vice-President, Mr. D. J. Scourfield, F.Z.S.,
F.R.M.S., in the chair, the minutes of the meeting held on
April 27th were read and confirmed.
QUEKETT MICROSCOPICAL CLUE. (361
Messrs. Sydney Harold Robinson, Walter E. T. Hartley and
John F. Donald Tutt were balloted for and duly elected mem-
bers of the Club.
The Hon. Secretary announced the presentation to the Club's
Cabinet of a further five slides of rare mosses by Mr. G. T. Harris.
Also an addition to the Club's album of a photograph of Mr.
G. C. Karop, who was Secretary of the Club from 1883 until
February 1904.
Mr. Seabury Edwardes, F.R.M.S., contributed a paper giving
some practical details on mounting diatoms in phosphorus. The
paper was read in abstract by the Hon. Secretary, but whether
any member has the temerity to put Mr. Edwardes' directions to
a practical test seems very doubtful. The results even on the
author's showing are somewhat problematical, and the process
very dangerous. It is hardly likely to come into use, as there
are simpler methods of mounting diatoms in high refractive
media.
Further notes on the cultivation of plasmodia of Badhamia
utricular is were given by Mr. A. E. Hilton. A year ago he
called attention to a method of cultivating this plasmodium on
bread, with occasional applications of a solution of ammonium
phosphate and cane-sugar. In the discussion following, two
points were raised which he was unable to answer. One was
whether this particular species of Mycetozoa could be obtained
by the cultivation of spores ; the other, whether it would, when
artificially fed, form sporangia. As a result of further investiga-
tion, Mr. Hilton stated that it is possible to cultivate the spores,
but not always easy. With regard to the second question,
whether it would form sporangia when artificially fed, he was
now able to state that it would, but with certain reservations.
On February 19th last a plasmodium of B. utricularis was started
by reviving a fragment of sclerotium, which was treated entirely
with bread and water and the chemical solution, adding, how-
ever, calcium phosphate, with a view to supplying the lime
usually found in this form of sporangium. The cold weather
made growth slow ; but on May 5th the plasmodium changed
into a quantity of sporangia. There are striking differences
between these and those produced under natural conditions.
The shape is similar ; but instead of the usual cinereous hue,
they are a dull purple-black, cinnamon-brown, or even pale
662 PROCEEDINGS OF THE
biscuit tint. All are sprinkled with white crystalline particles. '
The sporangium walls, usually very thin and fragile, are hard,
thick and chippy, and there is no distinguishable capillitium.
They are also only about half the ordinary diameter. The
spores themselves, generally bright brown and spinulose, are
smooth and almost colourless, but quite the usual size, if not
slightly larger, and in other respects appear perfectly normal.
Mr. Hilton had not yet attempted to cultivate these spores.
The Hon. Secretary then read a paper on Hydrodictyon reti-
culatum, or utriculatum. Last September he found an immense
quantity of this alga in the lake in Kew Gardens. According
to Dr. Cooke the " water-net " is one of the earliest enumerated
freshwater algae in Britain. It is figured in PlukeneFs Alma
Geslum in 1691, and was again mentioned by Bobart in 1699.
Ray includes it in his " Synopsis " in 1724 as Conferva reticulata,
and says that it was found in ditches about Westminster and
Hounslow. Owing to various characteristics which are not
found in other algae, Hydrodictyon has been placed in a sub-
family by itself. It consists of a saccate net-like object varying
in size from almost microscopic up to a length of several inches.
The cells also vary in size when young from 8 /j. to 10 /x in diameter
and grow sometimes to a length of 1 cm. — say, 2/5th-in. They
are approximately cylindrical in shape, and are arranged with
their ends in contact, usually three meeting at such an angle
as to form the typical hexagonal meshes. They have a some-
what thick wall, and inside a layer of protoplasm, in which the .
green chlorophyll is diffused, not collected into definite chloro-
plasts as usual in algae. The centre is filled with cell sap. The
protoplasm contains numerous and quite typical pyrenoids
each consisting of a central body with a layer of starch-grains
outside. These may be considered as food reserve. At the
commencement of reproduction they disappear, and are obviously
used up. There is also fine-grained starch in the protoplasm,
used for the purposes of life and growth. Many nuclei are pre-
sent in each cell. The net is born with a certain number of
cells, and always continues the same ; if, owing to injury, a part
is destroyed, it is not replaced. A small, complete net, con-
sisting, it may be, of some thousands of cells, is formed inside
each of the members of the original net. The mother cell-wall
gelatinises, and the young one is set free. What causes the ap-
QUEKETT MICROSCOPICAL CLUB. 663
pearancc or disappearance of Hydrodictyon is not understood.
After being very plentiful it will totally disappear perhaps for
several years, and then there is a sudden reappearance. These
outbreaks are known in some parts as the " breaking of the
meres." For instance. Hydrodictyon appeared formerly in
the lake in Kew Gardens. Mr. Burton has looked for it for
more than thirty years there, and only found one very small
specimen up to last autumn, when a tremendous outbreak
occurred. In less than four weeks, however, it had all disap-
peared. He suggested that the probable explanation was a
combination of several favourable circumstances which do not
frequently arise, possibly some special type of weather and
some narrow range of temperature at a particular season.
Mr. F. J. Perks (Hon. Treasurer) read some Notes by Mr.
E. M. Nelson on various insect structures. The wing of the
Neuropteron, Agrion pulchdlum, he pointed out, is a very
interesting microscopical object. The membrane is double,
bordered by a rim edged with saw-like teeth, the surface is
divided by nervures which are peculiar — the transverse bars, as
well as four longitudinal, have on one edge thorns, and on the
other saw-like teeth ; three other longitudinal ribs have saw-
teeth on one edge and fine teeth on the other, but no thorns. At
one part on the edge of the wing is a dark-coloured compartment
improperly called Ci stigma." This is really a pocket, and is
obviously used for producing a sound. If the border of the
wing is examined through a half-inch objective and a x 10 eyepiece,
a delicate hair can be seen between the teeth of the saw, very
minute, the largest found measuring 23 /x in length and 2 /x in
breadth. They spring out of circular rings, as do most insect
hairs, but not like those on the membrane of a blowfly's tongue,
which have no rings. Mr. Nelson points out that careful ex-
amination of the small hairs on the wing of a wasp will show
they are twisted like the tusk of a narwhal. The hairs on a
bee's wing are similar, but not so twisted, while they have no
ring. Those on the wing of a saw-fly issue from a boss. The
hairs on the ovipositor of Phalangia have a ringed base, and'
on the last two terminal stripes, where the hairs are larger, the
ringed boss has a circle of minute hairs. The hair itse f is
tubular, has a filamentous end, and at the side there is a minute
prong. At the end of each of the two lobes of the ovipositor
664 PROCEEDINGS OF THE
is a small boss covered with minute hairs, without ring bases/
and bluntened, probably open ; they have internal ring (not
spiral) structure similar to an artery. The examination of the
mandibles of a gadfly, Tabanus bovinus, will show the most
wonderful saw in the world, having 10,000 to 16,000 teeth per
inch on one edge, while the other is the keenest blade in exist-
ence. After describing the sting of a hornet, Vespa crabro,
he draws attention to the pygidium of a flea. If the right- and
left-hand edges are examined, a Eustachian tube will be seen.
The apparatus corresponds to the drum of an ear, and must
have an air-passage to equalise the pressure on either side. At
the base of the haltere in a blowfly a similar tube is easily seen.
At the 509th Ordinary Meeting of the Club, held on June 22nd,
1915, the President, Professor Arthur Dendy, D.Sc, F.R.S.. in
the chair, the minutes of the meeting held on May 28th were
read and confirmed.
Mr. Reginald Arthur Price was balloted for and duly elected
a member of the Club.
The President stated that, as the first meeting to consider
the formation of the Club was held on June 14th, 1865, the
present meeting marked an epoch in the history of the Quekett
Club, as it concluded the first fifty years of work, and all who
knew would agree that it had been to them a half-century full
of important results, and that the present condition of the Club
was very satisfactory. Most of the members present knew that
the Committee had begun to arrange for the celebration of this
event, but they had since thought it necessary to abandon the
idea, as it was felt that any kind of rejoicing would be out of
harmony with the prevailing feeling at the present time, and
he thought they would all be agreed that the most dignified
thing they could do under the circumstances was to defer that
celebration. He wished also in the first place to say that the
Hon. Editor had inserted in the last number of the Journal a
very interesting account of the early history of the Club, which
would no doubt be read with great pleasure by the members.
Another point was that they had the pleasure of seeing that
evening present at their meeting three of the original members
of the Club— Mr. R. T. Lewis, who had acted as their Honorary
QUEKETT MICROSCOPICAL CLUB. 663
Reporter from its commencement, Mr. Alpkeus Smith, who was
their Honorary Librarian for forty years, and Mr. Thomas
Powell, whom they all had the pleasure recently of congratulating
upon the attainment of his eightieth birthady. He hoped they
would long be able to attend the meetings of the Club.
Dr. John W. Evans, of the Geological Department of the
Imperial College of Science, South Kensington, then gave a
lecture on '; The Microscopical Examination of Minerals."
Dr. Evans stated that for many reasons a stationary stage
and revolving nicols are most convenient, but add greatly to
expense, and he found high-power objectives of great use for
special examinations. Tube and eyepiece must be provided
with a slot, so that a quartz wedge, gypsum plate, or eyepiece
micrometer may be inserted in the focus of the eyepiece. This
slot should be placed in a diagonal position, and not, like in
many foreign instruments, from left to right, which makes
special wedges and plates necessary. A good rock slice should
range between 20 and 30 microns in thickness, but with trans-
parent minerals much thicker sections may be usefully em-
ployed. For examination the section should be brought into
the centre of the field, so that it lies beneath the intersection
of the crossed wires, and the stage rotated until the index read-
ing is zero. If with both nicols in the crossed position and
the stage rotated the crystal section remain dark through a
complete rotation, it is either isotropic or cut at right angles
to the optic axis of a uniaxial crystal. If it continue uniformly
faintly illuminated, it is at right angles to an optic axis of a
biaxial crystal. Usually it will be dark at four points in the
rotation when the directions of vibration of light traversing
the crystal section are parallel to those of the nicols. These
four points are known as " extinctions.''
There is usually some difficulty in determining the position
of maximum darkness corresponding to the true position of
extinction, and one of the simplest of many methods is to rotate
the stage towards the position of extinction alternately from
opposite directions and to note the readings on each side where
the same degree of obscuration has been obtained. The mean
of several pairs of observations will give approximately the
true position.
Ascertain which of the extinctions or directions of vibration
666 PROCEEDINGS OF THE
in the crystal section is the direction of vibration of light with '
the greater velocity, and which that of light with the less velocity,
and determine, at the same time, the relative retardation, or, in
other words, how far the slower moving vibrations have lagged
behind the faster. (This is usually measured in micro-milli-
metres, or millionths of a millimetre.) For the purpose of
making these determinations we insert both nicols in the cross
position and rotate the stage till the direction of vibration is
diagonal to those of the nicols. The two vibrations which pass
the lower nicol are now resolved along the two directions of
vibration of the section. If there were no relative retardation
they would in emergence recombine to form a vibration parallel
to the same direction as before, and would be extinguished by
the upper nicol. As a result of the relative retardation, however,
the various colours of the spectrum are transmitted in different
degrees, so that the compound tints known as interference
colours are obtained. These are dependent upon the amount
of it, which is usually about the same for all colours of the
spectrum.
Interference colours commence with complete darkness at
zero relative retardation and pass through grey, white, yellow,
orange and red, which last is seen when the relative retardation
reaches 550 micro-m.m. These constitute the colours of the first
order. Then followr purple, violet, blue, green, yellow and red
up to a relative retardation of 1,000. These are the second
order. Every addition of 550 micro-m.m. corresponds to another
order with a similar succession of colours, gradually becoming
more complex until they are delicate shades of green and pink,
and with a relative retardation of about 4,000 micro-m.m. they
slowly pass into white light.
If one nicol be rotated through a quarter turn so that the
directions of vibrations of the two nicols are parallel, the colours
are seen to pass through brown, red and blue to the yellowish
green, marking the end of the first order at 550. Then the
second, and gradually the colours fade into white light, exactly
as with crossed nicols.
The amount of relative retardation in a crystal section may
be roughly estimated directly from the interference colours
between crossed and parallel nicols by comparison with tables
or lithographic plates of colours giving the corresponding
QUEKETT MICROSCOPICAL CLUB. 667
relative retardations (one was exhibited at the lecture), but in
determining colours so much depends upon the idiosyncrasy
of the observer, and the character of the light, that results
can only be relied on within very wide limits. In the smoky
atmosphere of a London winter, for instance, the blue of the
second order appears to pass into greenish yellow without any
definite green intervening. Relative retardation is equal to the
product of the thickness of the section and the birefringence,
which is the relative retardation in a unit of distance, and is
equal to the difference between the refractive indices of the
two directions of vibration. In the case of a section of quartz
21 microns thick, cut parallel to the optic axis, the indices of
refraction are 1*544 and 1*553, and the bi-refringence therefore
0*009. Accordingly the relative retardation = 21 x 0*009 = 0*189
of a micron. For the purposes of determining the character of
extinctions and the amount of relative retardation a quartz
wedge or mica ladder may be employed.
Dr. F. E. Wright, of the Smithsonian Institute, Philadelphia,
devised a combination of quartz wedge and gypsum, and Dr.
Evans has successfully employed the same idea.
A quartz wedge is superposed on a gypsum plate, both being
constructed with the usual orientation, so as to leave beyond
the* thin end of the wedge a square of gypsum, which may be
used as an ordinary gypsum plate. The quartz will show a
black band where it neutralises the gypsum. The point is
marked zero. Every hundred micro-m.m. of relative retarda-
tion is shown either way. If the direction of the crystal section
parallel to the slot be fast, the band wrill move towards the thick
end of the wedge ; if slow, towards the thin end.
The mica ladder consists of a succession of narrow cleavage
plates of muscovite, with their length cut parallel to the trace
of the optic axial plane, and therefore slow. Each strip should
have a relative retardation of 100 micro-m.m. They are of
different lengths and superposed to form a succession of steps
each large enough to cover the whole cone of light in the lower
slot, where they are usually employed, though useful in the
focus of the eyepiece, if the upper nicol be placed above them.
In either case they show a discontinuous series of colours corre-
sponding to differences of 100 micro-m.m. If inserted over a
section it is easy to show whether the two show additive or
668 PROCEEDINGS OF THE QUEKETT MICROSCOPICAL CLUB.
subtractive relations. In the former case the stage should be
rotated till the fast direction of the section is parallel to the slot.
It may happen, then, that the section is neutralised by one of
the steps, and therefore is of the same relative retardation. If
one step just fails to neutralise and the next higher will more
than do so, and neither are completely dark, then if they be
equally bright, the relative retardation must be midway between ;
if one is darker, then it will be proportionately nearer to that
step. In this way the relative retardation can be estimated to
within 20 or 30 micro-m.m. When the directions-image — i.e.
the object viewed without an eyepiece reflected on the back
lens of the objective — is examined between crossed nicols, it
shows in the centre of the field the same interference colours as
that seen in the object image. The colours move with the stage
as it rotates without suffering any changes of configuration,
x^t the same time the field is traversed by dark bands or
brushes, which constitute the isogyre. As the rotation proceeds,
these change both their position and their shape and may from
time to time leave the field altogether. When the stage is in
the position corresponding to extinction in the object-image or,
in other words, when the vibrations in the section are parallel
to the cross wires, the isogyre passes through the centre of the
field and is known as a ': central isogyre."
Dr. Evans concluded his lecture by describing the technical
indications of the different isogyres.
The lecture was fully illustrated by diagrams and coloured
lantern slides, which were, Dr. Evans pointed out, mostly due
to the art of Mr. C. H. Caffyn.
There was a collection of photographs of rock sections on
Lumiere Autochrome plates, exhibited by Messrs. J. W. Ogilvv
and C. H. Caffyn, and also a series of exhibits showing the pro-
cess of mounting a rock section.
669
OBITUARY NOTICE.
EDWARD ALFRED MINCHIN, M.A., F.R.S.
{Born February 2V>th, I860; died September 30th, 1915.)
The members of the Quekett Microscopical Club will have heard
with the deepest regret the sad news of the death of our former
President, Professor E. A. Minchin, MA., F.R.S. , which took
place on September 30th at Selsey, at the comparatively early
age of forty-nine.
Professor Minchin was one of the most distinguished men of
science who have ever occupied the presidential chair of this
Club, and his stimulating addresses will long be remembered by
those of us who were privileged to hear them, while the kindly
courtesy with which he was always ready to share his unrivalled
knowledge of his special subjects endeared him to all his fellow -
workers. It is to Professor Minchin that I owe my own intro-
duction to the Club, and it may interest my fellow-members to
hear of the cordial appreciation with which he spoke to me of the
Club and its work. It was quite evident that he derived a very
real satisfaction from his association with its members.
The Quekett Club, however, formed but a small part of the
field in which Professor Minchin exercised his scientific activities.
Both as a teacher and as an original investigator of the first rank,
he was well known to zoologists in all parts of the civilised world.
His luminous general treatises, especially those on the Sponges
and the Protozoa, are landmarks in the progress of zoological
science, while at the same time his own researches have broken
new ground in many directions.
He was, I think, the most conscientious investigator that I
have ever had the good fortune to meet. In the study of Spong-
ology in particular he introduced a standard of painstaking
accuracy that was sorely needed, and set an example of thorough-
ness that will be hard indeed for those who follow him to emulate.
His most striking and important contributions to this depart-
ment of zoology are his beautiful researches on the histology
670 OBITUARY NOTICE.
and embryology of the Calcarea, especially those dealing with
the origin and development of the triradiate spicules, or, rather,
spicule-systeins, as he showed them to be. The conclusions at
which he arrived as the result of these investigations were of a
startling and wholly unexpected nature. His most important
memoirs on Sponges were produced while he occupied the chair
of Zoology at University College, London, and it was, I know, no
small grief to him to have to abandon these researches, at
any rate to a large extent, when he accepted the newly created
chair of Protozoology in the University of London and trans-
ferred his headquarters to the Lister Institute of Preventive
Medicine at Chelsea.
While at University College he had already won a great reputa-
tion as a student of the Sporozoa, a group of Protozoa which in
recent years has assumed such immense imj>ortance from the
medical standpoint, and at the Lister Institute the parasitic
Protozoa necessarily claimed his chief attention. Here his wonder-
ful mastery of microscopical technique stood him in good stead,
and his exquisitely illustrated memoirs on the Trypanosomes,
published in The Quarterly Journal of Microscopical Science,
would alone form a lasting monument to his industry and skill.
His work in this direction took him far afield, for even before he
resigned his chair at University College he had visited Uganda
as a member of the Royal Society's Commission on Sleeping
Sickness. His Introduction to the Study of the Protozoa, with
special reference to the parasitic forms, published in 1912, will long
remain the standard treatise on this most important subject.
The amount of hard work that Minchin managed to get through
is marvellous. In spite of his delicate health and his preoccupa-
tion with original research of the most intricate and difficult
character, and in addition to his numerous duties as a teaching
professor, he managed to find time to take an active part in the
work of scientific societies. His zeal and energy as President of
the Quekett Microscopical Club are fresh in the memories of all
of us, but he was also a Vice-President of the Zoological Society
and latterly Zoological Secretary of the Linnean Society.
Minchin' s last contribution to science was his Presidential
Address to the Zoological Section of the British Association at
Manchester, in September last. Those of us who were present
on that occasion knew that the end was not far off, and it was with
OBITUARY NOTICE. 671
sad feelings that we listened to his friend Mr. Heron- Allen, whom
Minchin had chosen to read the address on his behalf. -In this
address the departing master summed up his views on that
fascinating subject, the evolution of the cell, and showed us,
what indeed we all knew before, that he was not only a specialist
of the highest type, but gifted with a deep insight into the funda-
mental problems of his beloved science.
A. D.
673
INDEX.
A
I 'AGE
Abbe, Prof. On the Aperto-
meter . . .288
Acercus longiiarsus sp. nov. 140
Actinocyclus . . .28
Aclinocyclus Ralfsii and a
Coloured Coma. E. M.
Nelson . . . 100
Actinoptychus . . .36
Ayr ion pulchellum . . 593
Ainslie, M. A. A variation of
Cheshire's Apertometer 287
— An addition to the objec-
tive .... 561
Akehurst, S. C. A changer
for use with sub-stage
condensers . . .277
— Some observations con-
cerning sub- stage illu-
mination . . . 301
— A trap for free- swimming-
organisms . . . 27!)
Alveolina Boscii . . 9
A mphiplcura Lindheimcri
315, 330
Annual Report for 1912 . 113
1913 . . . 354
— —1914 . . . 558
Apertometer, Cheshire's, an
improved form. E. 31.
Nelson . . .281
A variation of. M. A.
Ainslie . . . 287
Apertometers for dry len-
ses, Two simple. F. J.
Cheshire . . . 283
Arachnoidiscus ornatus, Ab-
normal form of . . 414
arbor icola, Moraria . . 434
Arrhennrus Scourfieldi sp.
nov. . . . .139
Asplachna Silvestrii . . 61
Jourx. Q. M. C, Sertes II.
Fos-
mea-
Asteromphalus .
A hlacodiscus Combcri, Ter-
tiarv structure of
B
Bacterium termo, fiagella of,
diameter of
Badhamia utricularis, Cul-
tivation of plasmodia
of. A. E. Hilton
Plasmodium of
Baker, W. E. Watson,
sils from the coal
sures ....
Bale, W. 31. Notes on some
of the Discoid Diatoms
Bastian, Dr. Charlton
Bilfingeri, Callidina .
Binocular Microscopes. E.
31. Nelson .
Bi-refrinqence .
Borley, J. O. Note by, on
f ora minifera 1 dredging s
Brachionus, Description of
a new. C. F. Rousselet
Brachionus ytcrodinoid.es sp.
nov. .
■ — satanicua
Brown, N. E. Some notes
on the structure of Dia-
toms ....
— Fertilisation of Vinca
minor ...
Bryce, 1). On five new
species of Bdelloid Roti-
fera ....
— On five new species of the
genus Habrotrocha
Brvological
work, Micro-
scopical methods in.
G. T. Hanis
PA K
35
577
391
381
585
41S
17
272
92
369
625
137
57
59
59
317
412
S3
631
521
-No. 77.
38
674
INDEX.
Burton, J. On the disc-like
termination of the fla-
gellum of some Euglenae
— On a method of marking
a given object for future
reference on a mounted
slide ....
— Abnormal form of Arach-
noidiscus ornatus
— Hydrodictyon reticu latum
PACK
201
3 1 1
414
587
C
Cabinet, Additions to the Club
401, 646
Callidina Bilfingeri sp. nov. 92
Cambrian strata, Forami-
nifera of . .3
Ceratophyllus fasciatus, ana-
tomy of . .441
Changer for sub-stage con-
densers. S. C. Akehurst 277
Cheshire, F. J. Two simple
apertometers for dry
lenses . . . 283
Chiridota allani . . 106
— dunedinensis . . 106
Chlamydozoa . . .270
Clusius (Charles de l'Ecluse.
1526-1609). . . 10
Condenser, A new low-power.
E. M. Nelson . 95. 367
Condensers, sub- stage, A
changer for . . 277
Conversazione . . . 350
Copepod, A new, found in
water in hollows on tree-
trunks. D. J. Scour-
field . . . .431
Correlation of characters . 76
Coscinodiscus ... 7
Coscinodiscus asterom-phalus . 1 57
— heliozoides . . 108,331
Cover-glass, corrections for
thickness of . . 56S
D
Dendy, A. By-products of
organic evolution . 65
- On a new species of Holo-
thurian . . .105
- Organisms and Origins . 259
- A red- water phenomenon
due to Euglena . . 345
— The biological conception
of individuality . . 465
Devil's Lake, The Rotifera
of. C. F. llousselet
Diatoms, Discoid, Notes on.
W. M. Bale
— Notes on the structure of
N. E. Brown
Diatom structure. Notes on
A. A. C. Eliot Merlin
Directions-image. Bertrand
lens .
— Becke lens .
— Interference colours
— Isogvres
Discoid Diatoms, Notes on
W. M. Bale .
Draper, B. M. Dark-ground
illumination with the
Greenough Binocular .
— A live-box for the obser-
vation of insects and
similar objects .
E
Earland, A., s.v. Heron- Allen,
E.
Eidolic dots of interference
Eozoon canadense
Epidiascope.
Euglena viridis, Theflagellum
o' . . . .
As a cause of red
water
Evans, J. W. The deter-
mination of minerals un-
der the microscope by
means of their optical
characters .
Evolution, organic. By-pro-
ducts of. A. Dendy
F
Fine adjustment, side screw.
E. M. Nelson
Fissidentaceae, Notes on the
slides of. G. T. Harris
Flagellum of some Euglenae,
Disc-like termination of
the. J. Burton
flava, Habrotrccha
Foraminifera as world-
builders. E. Heron-
Allen and A. Earland .
— From the North Sea, On
some. E. Heron-Allen
and A. Earland .
PA R
57
17
317
577
615
615
617
617
17
313
313
386
2
104
291
345
597
65
96
581
291
639
121
INDEX.
G75
Foraminifera. Fossil forms
from the North Sea
G
Gastrotricha. J. Murray
— Form and structure
— Haunts and habits
— Classification
— Key to genera
— List of species
— Notes on certain species
— Bibliography
G lobigerina ooze
Gordon, J. W. A " new "
object-glass by Zeiss .
Grundy, J. A micrometric
table by E. M. Nelson .
H
Habrotrocha flava sp. nov
— insignis sp. nov.
— ligula sp.'nov
— longula sp. nov.
— munda sp. nov.
— pavida sp. nov.
— spicula sp. nov.
— sylvestris sp. nov.
— torquata sp. nov.
Harris, G. T. The collectio
and preservation of the
Hydroida .
— Microscopical methods in
bryological work
— A note on the slides of
Fissidentaceae in the
■ Q.M.C. Cabinet .
Keath, C. E. Safety device
for use with objectives.
Heron-Allen, E., and Earl-
and. A. The Foramini-
fera in their role as
world-builders
— On some Foraminifera
from the North Sea,
dredged b v the Fisheries'
cruiser Huxley
Hilton, A. E. Notes on the
cultivation of Plasmodia
of Badhamia utricular is
— Further notes on the cul-
tivation of the Plasmodia
of Badhamia utricularis
Hydracarina, British : The
genus Lebertia. W.Wil-
liamson and C. D. Soar
PAl i E
126
211
213
214
215
218
219
223
229
12
515
541
1)3!)
635
90
640
85
637
89
637
87
143
521
581
344
1
121
381
585
479
Hydrachnida {vide Water-
mites)
Hydrodictyon retic ulatum.
James Burton
Hydroida, The collection
and preservation of.
G. T. Harris
— Shore collecting
— Preparation and mount-
ing ....
— Notes on some species .
illumination, annular, for
sub- stage .
— Dark-ground, in the
Greenough Binocular .
— New method of
Individuality, The biologi-
cal conception of. A.
Dendy
Insect structures, various.
E. M. Nelson
insignis, Habrotrocha .
invaginata, Lagena
K
Koristka's new " loup '*
Lagenae of the South-west
Pacific Ocean. H. Side-
bottom
Lagena invaginata sp. nov. .
— maculata sp. nov. .
— renifonnis sp. nov.
— splendida sp. nov.
Lebertia (Hydracarina)
Lebertia celtica .
— fimbria ta
— glabra ....
— Halberti
— insignis
— obscura
— porosa ....
— Soari ....
— stigmatifera .
— tau-insignita .
— trisecta
Leitz concentric reflecting
condenser .
Lewis, R. T. The early his-
tory of the Quekett
Microscopical Club
IW.K
587
143
144
149
152
301
313
365
465
593
635
204
2.-,j
161
204
206
204
178
479
494
491
507
505
497
504
499
491
509
487
512
303
425
676
INDEX.
i'.V E
Lhwyd, Edward . . 259
Library, Recent additions
to ... 390
ligula, Habrotrccha . . 90
Live-box for observation of
insects . . .313
longitarsus, Acercus . .140
longula, Habrotrocka . . 040
.M
maculata, Lagena . . 206
Magnifying power of a mi-
croscope, Measuring the.
E. M. Nelson . .239
— of objectives. Initial mea-
surement of. E. M.
Nelson . . .295
Marking an object slide for
future reference . 311
Measures, English metrical
table for the conversion
of . . . 424
Merlin, A. A. C. Eliot, Se-
condary hairs on foot of
a Ceylon spider . . 252
— On the minimum visible 385
— Notes on diatom structure 577
Micrometric table . .541
Microscope construction, On.
E. M. Nelson . . 96
— new model. W. Watson
& Sons, Ltd. . . 108
Microscopes, Binocular . 369
Minchin, E. A. Some de-
tails in the anatomy of
the rat-flea (Ccrato-
phyllus fasciatus . 441
Minerals, Determination of,
by means of their optical
characters. J. W.
Evans . . . 597
Minimum visible, The 270, 385
"Mixon " reef, Selsey . 9
Monera . . . .268
Moraria arboricola sp. nov. 434
Mosses, Collecting . .521
— Preparation of slides . 523
— Notes on slides of 533, 581
munda, Habrotrocha . . 85
Murray, J. Gastrotricha . 211
N
Navicula rhomboides . 96, 315
— serians . . .329
PAGE
Nelson, B. M. A new low-
power condenser . 95
— On microscope construc-
tion and the side screw
fine adjustment . . 96
— Navicula rhomboides and
allied forms . . 90
— Note on Pleurosigma an-
gwlatum . . .98
— Actinocycliis Ralfsii and
a coloured coma . 100
— On a new method of mea-
suring the magnifying
power of a microscope 230
— An improved form of
Cheshire's apertometer 281
— On the measurement of
the initial magnifying
powers of objectives . 295
— Amphipleura Lindheimeri 3 1 5
— A new object-glass by
Zeiss and a new method
of illumination . .363
— A new low-power con-
denser . . .367
— Binocular microscopes . 369
— Palaeozoic fungi . . 546
— Various insect structures 593
Nitzschia scalaris . . 330
Notices of Books : Marcus
Hartog. Problems of
Life and Reproduction 101
— C. E. Heath. The Be-
ginner's Guide to the
Microscope . . 102
— H. Lloyd Hind and W.
Brough Randies. Hand-
book of Photomicro-
graphy . . . 339
— J. Cash and G. H. Wailes.
British Freshwater
Rhizopoda, vols, i.-iii.
(Ray Society) . . 643
Nummulitic limestone . 9
O
Obituary Notices :
Rt. Hon. Sir Ford
North . . 258
Dr. M. C. Cooke . . 422
F. W. Millett . . 559
Prof. E. A. Minchin . 669
Object-glass by Zeiss, A new.
E. M. Nelson . . 363
A " new." J. W.
Gordon . . .515
INDEX
677
Object-image, examination
of .
— Extinctions .
— Pleochroism .
— Relative retardation
— Quartz wedge
— Gypsum plate
— Mica steps
Objective, An addition to
th^. M. A. Ainslie
O'Donohoe, T. A. The min-
ute structure of Coscino-
di sc u s asteromphalus
and of the two species
of Pleurosigma, P. angu-
latum and P. balticum .
— An attempt to resolve
and photograph Pmnw-
laria nobilis
Oil-immersion into water-
immersion, Conversion
of
Organisms and Origins. A.
Dendy
— Filter-passing
— Terrestrial, their origin .
Osmotic growths, Artificial.
IW.F.
601
601
(KM
CO.-)
608
(ill
612
561
155
300
572
250
270
264
78
Palaeozoic fungi . . 546
Panspermia, Theory of . 264
pavida, Habrotrocha . . 637
Pedalion ou Pedalia. C. F.
Rousselet . . ,397
Pinnularia major . . 317
— nobilis . . .309
An attempt to resolve
and photograph. T.
A. O'Donohoe . . 300
Plasmodia, Cultivation of
381, 585
— reversing currents, Ex-
hibition of . . . 383
Plasmodium of B. utricular is,
Cultivation of. A. E.
Hilton . . . 585
Pleurosigma angulatum
Proceedings. Oct. 1913-
Feb. 1914 .
— Mar. 1914 — Tunc 1914
— Oct. 1914— Feb. 1915
— Mar. 1915 — lune 1915
pterodinoides, Brachiou us
Q
Quekett Microscopical Club,
Early History of. R. T.
Lewis
— History
of
R
PAGE
340
41 1
537
653
59
425
419
98, 159,
325
— balticum . . 159,
319
President's Address, 1913.
Arthur Dendy .
65
1914. Arthur Dendy
259
1915. Arthur Dendy
465
Proceedings. Oct. 1912 —
Feb. 1913 .
103
— Mar. 1913— June 1913 .
245
Rat-flea, some details in the
anatomy of. E. A.
Minchin . . .441
— abdominal nervous sys-
tem .... 447
— dissection of . .442
— female reproductive or-
gans . . . 457
— male reproductive organs 452
— preparation of tissues . 443
— salivary glands . . 450
— stellate muscles in oeso-
phagus . . .460
Ray. John. Three Physico-
Theological Discourses . 259
Refractive index . . 625
reni for mis, Lagena . . 204
Report on the Conference
of Delegates (Havre) . 395
Rhabdites . . .46
Rhabdocoelida. British
Fresh-water. H. White-
head . . .45
Rotifera of Devil's Lake.
C. F. Rousselet . . 57
— Bdelloid, Five new species
of. D. Brvce 83, 631
Rousselet, C. F. The Roti-
fera of Devil's Lake,
with Description of a
new Brachionus . . 57
— Remarks on two species
of African Volvox . 393
— Report on the Conference
of Delegates of Corre-
sponding Societies held
at Havre . . . 395
— Pedalion ou Pedalia : une
question de nomencla-
ture dans la classe des
Roti feres . . .397
078
INDEX.
PACE
S
Scourfield, D. J. A new
Copepod found in
water from hollows in
tree trunks
Scourfieldi, Arrhcnurus
Sidebottom, H. Lagenae of
the South-west Pacific
Ocean (Supplementary
Paper)
Soar, C. D. Description ot
Arrhcnurus Scourfieldi
and Acercus longitarsus.
Two new species of
water- mites
— s.v. Williamson, W.
Sperchon, the genus, New
records for .
" Spheres " from the chalk
spicula, Habrotrocha .
splendida, Lagena
Sponge-spicules, Shape and
evolution of
— scleroblasts and mother-
cells ....
— specific differences
Spontaneous generation,
Theory of .
Stauroneis phoenicentron
Surirella gemma
sylvestris, Habrctrccha
T
Tabanus bovinus
Taeniogyrus Allani
Test objects, Diatoms first
used as
torquata, Habrotroch'i
Trap for free-swimming or-
ganisms. S. C. Ake-
hurst
431
131)
161
139
141
8
89
178
67
73
74
205
331
327
637
595
10G
579
87
279
Travis, W. R. Simple ap-
paratus in pond- hunt-
ing .
— On quartz crystals .
Treasurer's Report for 1912
1913
1914
Triceratium favus
Trichodina pedicvlus .
— Steinii
Trichopteryx atomaria
Trochodota dunedincnsis
Tube-length, correct, Impor-
tance of
Turbellaria {vide Rhabdo-
coelida)
V
PA.aH
256
348
120
354
558
332
545
545
595
105
562
413
Vinca minor, Fertilisation of
Volvox, African, Two species
of. C. F. Rousselet 393
Volvox africanns . .393
— Rousseleti . . . 394
W
Water-mites, Description of
two new species. C. D.
Soar ....
l' Wheel-plates " in Holo-
thurians. Development
of ... .
Whitehead, H. Some notes
on British freshwater
Rhabdocoelida, a group
of Turbellaria
— An epizoic Infusorian .
Williamson, W., and Soar, C
D. British Hydrocar-
139
106
45
545
ina : the scenus Lebertia 479
OEEICERS AND COMMITTEE.
{Elected February 1914.)
President:
Prof. Arthur Dendy, D.Sc, F.R.S.
Vice-Presidents :
C. F. Rousselet, Curator R.M.S.
Edmund J. Spitta, L.R.C.P., M.R.C.S., F.R.M.S., F.R.A.S.
D. J. Scourfield, F.Z.S., F.R.M.S.
Prof. E. A. Minchin, M.A., Ph.D., F.R.S.
COIVIIVIITTEE :
C. H. Bestow, F.R.M.S.
M. Blood, M.A., F.C.S., F.R.M.S.
N. E. Brown, A.L.S.
D. Bryce.
J. Grundy, F.R.M.S.
E. Heron-Allen, F.R.M.S.,
F.L.S., F.Z.S., F.G.S.
R. Inwards, F.R.A.S.
A. Morley Jones.
J. M. Offord, F.R.M.S.
R. Paulson, F.L.S., F.R.M.S.
C. D. Soar, F.L.S., F.R.M.S.
J. Wilson, F.R.M.S.
Hon. Treasurer :
Frederick J. Perks, 48, Grove Park, Denmark Hill, S.E.,
to whom subscriptions should be sent.
Hon. Secretary:
James Burton, 8, Somali Road, West Hampstead, N.W.,
to whom all correspondence should be addressed.
Hon. Assistant Secretary:
J. H. Pledge, F.R.M.S., 72, Nibihwaite Road, Harrow, Middlesex.
Hon. Sec. for Foreign Correspondence:
C. F. Rousselet, Curator R.M.S. , Fir Island, Mill Hill, N.W.
Hon. Reporter :
R. T. Lewis, F.R.M.S., 41, The Park, Ealing, W.
Hon. Librarian :
S. C. Akehurst, F.R.M.S., 60, Bowes Road, Palmers Green, N.
Hon. Curator :
C. J. H. Sidwell, F.R.M.S. 46, Ashbourne Grove, Dulwich, S.E.
Hon. Editor :
A. W. Sheppard, F.Z.S., F.R.M.S., 1, Vernon Chambers, W.C.
a
11
PAST PRESIDENTS.
Elected
July 1865.
., 1866.
? ?
/?
JS
}J
1867-8.
1869.
1870-1.
1872-3.
1874-5.
1876-7.
1878.
1879.
♦EDWIN LANKESTER, M.D., F.R.S. .
♦ERNEST HART ....
♦ARTHUR E. DURHAM, F.R.C.S., F.L.S.
♦PETER LE NEVE FOSTER, M.A. .
♦LIONEL S. BEALE, M.B., F.R.S.
ROBERT BRAITHWAITE, M.D., F.L.S.
♦JOHN MATTHEWS, M.D., F.R.M.S. .
♦HENRY LEE, F.L.S., F.G.S., F.R.M.S., F.Z.S
♦THOS. H. HUXLEY, LL.D., F.R.S. .
♦T. SPENCER COBBOLD, M.D., F.R.S
T .L.O. ......
T. CHARTERS WHITE, M.R.C.S., L.D.S
F.R.M.S. .....
M. C. COOKE, M.A., LL.D., A.L.S. .
♦W. B. CARPENTER, C.B., F.R.S.
A. D. MICHAEL, F.L.S., F.R.M.S. .
B. T. LOWNE, F.R.C.S., F.L.S. .
*Rev. W. H. DALLINGER, LL.D., F.R.S.
x .R.M.S. .....
EDWARD MILLES NELSON, F.R.M.S.
*J. G. WALLER, F.S.A.
JOHN TATHAM, M.A., M.D., F.R.M.S.
GEORGE MASSEE, F.L.S. . . Feb. 1900-1-2-3.
EDMUND J. SPITTA, L.R.C.P., M.R.C.S.,
F.R.A.S., F.R.M.S. , . . Feb. 1904-5-6-7.
E. A. MINCHIN, M.A., F.R.S. . . Feb. 1908-11
* Deceased.
5>
J5
1880-1.
1882-3.
1884.
„ 1885-6-7.
Feb. 1888-9.
„ 1890-1-2.
„ 1893-4-5.
„ 1896-7.
1898-9.
J5
Ill
HONORARY MEMBERS.
Date of Election.
Jan. 24, 1868. Arthur Mead Edwards, M.D.
423, Fourth Avenue, Newark, New
Jersey, U.S.A.
Feb. 17, 1S93. Robert Braithwaite, M.D., F.L.S., F.R.M.S.
{Past President)
26, Endymion Road, Brixton Hill, S.W.
Feb. 17, 1893. M. C. Cooke, M.A., LL.D., A.L.S. {Past
President)
38, Lindley Avenue, East Southsm, Hants.
Feb. 17, 1893. T. Charters mite, M.R.C.S.,L.D.S., F.R.M.S.
(Past President)
49, Victoria Road South, Southsea.
Mar. 19, 1897. B. T. Lowne, M.D., F.R.C.S., F.L.S. (Past
President)
91, Carlisle Road, Hove, Sussex.
May 18, 1906. Dr. Eugene Penard
Rue Topfjer 3, Geneva.
Jan. 23, 1912. Alpheus Smith
14, Leigham Vale, Streatham, S.W,
April 23, 1912. Fred Enock, F.L.S., F.R.M.S., F.E.S.
13, Tufnell Park Road, Holloway, N.
IV
LIST OF MEMBERS.
Date of Election.
Feb. 16, 1906. Abson, Herbert
14, Gainsborough Road, Mile End, E.
Dec. 23, 1913. Ainslie, Maurice Anderson, R.N., B.A.,
F.R.A.S.
8, Woodville Road, Blackheath St.
Feb. 16, 1906. Akehurst, Sydney Charles, F.R.M.S. (Hon.
Librarian)
60, Bowes Road, Palmer's Green, N.
Feb. 19, 1904. Allardice, Lieut. William McDiarmid
Tregenna Longer oss, St. Endellion Norths
Cornwall.
May 24, 1910. Allen, William Nassau
" Caerneagh," North Circular Road>
Dublin.
Jan. 28, 1913. Allison, Arthur Morris
8, Sidney Road, Beckenham.
Dec. 15, 1899. Angus, H. F., F.R.M.S.
83, Wigmore Street, Cavendish Square, W+
Mar. 24, 1914. Anthes, Ernst Hermann
21, Lancaster Road, Hampstead, N.W.
Feb. 25, 1913. Armitage, John Joseph, L.D.S.E.
5, Cavendish Place, W.
June 21, 1907. Arpin, John Edward
131, Castelnau, Barnes, S.W.
Feb. 22, 1889. Ashe, A., F.R.M.S.
55, Warrior Square, Southe?id-on-Seai
Feb. 28, 1911. Austin, Henry
Tudor House, 120, Greenwich Road>
Greenwich, S.E.
Date of Election.
* .
June 4, 1909. Baddeley, William H. L.
29, Church Crescent, Church End, Finch-
ley, N.
April 17, 1903. Bagshaw, Walter, J.P., F.R.M.S.
" Moor field," Birkenshaw, near Bradford,
Yorks.
Sept. 26, 1884. Baker, F. W. Watson, F.R.M.S.
313, High Holborn, W.C.
Mar. 16, 1906. Baker, Henry James
13, Moorgate Street, E.G.
April 2, 1909. Baker, Wilfred E. Watson
313, High Holborn, W.C.
Nov. 25, 1913. Bale, Wm. Urontier, F.R.M.S.
63, Walpole Street, Kew, Victoria, Aus-
tralia.
June 19, 1908. Banhani, Edward Elliott
128, Uxbridge Road, West Ealing, W.
May 28, 1912. Barnard, Edward Jas.
10, Denver Road, Stamford Hill, N.
Feb. 25, 1913. Barnard, Joseph Edwin, F.R.M.S.
Park View, Brondesbury Park, N.W.
Mar. 19, 1886. Barnes, W.
23, Jackson Road, Holloway, N.
May 28, 1912. Barratt, Kenneth Franklin
" Bell Moor," Hampstead Heath, N.W.
May 28, 1912. Barratt, Thos. Franklin
" Bell Moor," Hampstead Heath, N.W.
Sept. 27, 1872. Bartlett, Edward, L.D.S., M.R.C.S.E.
38, Connaught Square, W.
Nov. 26, 1912. Bassett, Ernest Henry
" Pro tern," Amberley Road, Palmer's
Green, N.
June 17, 1892. Bates, C.
1, Windsor Road, Denmark Hill, S.E.
Oct. 18, 1895. Baugh, J. H. A.
63, Bambridge Road, Hammersmith, W .
June 4, 1909. Baxendale, Frederick G.
22, Holmesdale Avenue, East Sheen.
Jan. 16, 1891. Baxter, W. E., F.R.M.S,
170, Church Street, Stoke Newington, N.
VI
Date of Election.
June 19, 1908. Bayliffe, John H.
Nov. 26, 1875. Beaulah, John
Albert House, Brigg.
July 25, 1884. Beck, C, F.R.M.S.
68, Comhill, E.G.
Nov. 26, 1912. Bellamy, Geo. Claxson
16, Great Ormond Street, W.C.
June 27, 1911. Bennett, Lionel C.
49, Erpingham Road, Putney, S.W.
Feb. 16, 1906. Bestow, Charles H., F.R.M.S.
43, Upper Clapton Road, N.E.
June 16, 1905. Blair, William Nisbet
23, West Hill, Highgate, N.
Oct. 2, 1908. Blockley, Edgar A.
26, Mayfield Avenue, Chiswick, W.
May 19, 1899. Blood, Maurice, M.A., F.C.S., F.R.M.S.
8, Chichele Road, Cricklewood , N.W.
Feb. 25, 1913. Booker, Alfred James
37, Claremont Road, Highgate, N.
April 25, 1911. Bowtell, Alexander Jas.
123, Dalston Lane, N.E.
Nov. 15, 1907. Bradford, William Barnes
65, Tyrwhitt Road, St. John's, S.E.
Nov. 17, 1905. Bremner, John Unthank
277, King Street, Hammersmith, W.
Jan. 24, 1911. Bridge, Samuel
28, Larkhall Rise, Clapham, S.W.
Nov. 6, 1908. Broad, John Moxon
2, Nicoll Road, Harlesden, N.W.
May 28, 1912. Brooke, Thos. Robinson
12, Warren Road, Chingford, N.E.
Dec. 4, 1908. Brooks, Theodore, F.R.M.S.
British Vice-Consul, Guantanamo, Cuba.
Dec. 19, 1890. Brough, J. R.
" Eversley," Shepherd's Hill, Highgate, N.
Mar. 15, 1907. Browett, William
" Beaumont," Pear field Road, Forest
Hill, S.E.
May 24, 1910. Brown, Edward George
8, Freke Road, Battersea, S. W.
VI 1
Date of Election.
Jan. 18, 1907. Brown, Nicholas Edward, A.L.S.
6, The Avenue, Kew.
Jan. 28, 1887. Browne, E. T., M.A., F.R.M.S.
Anglefield, BerkJiamsted, Herts.
Mar. 18, 1904. Brushfleld, N. W.
13, All farthing Lane, Wandsworth Com-
mon, S.W.
Jan. 15, 1892. Bryce, David
37, Brooke Road, Stoke Newington, N.
May 28, 1912. Bull, Albert Edwd.
3, Canterbury Terrace, Sudbury, Harrow,
May 23, 1911. Bunnin, Charles A.
113, Newlands Park, Sydenham, S.E.
May 15, 1908. Bunting, Percival J.
" Lyndhurst," Birches Barn Road, WoU
verhampton.
Jan. 20, 1905. Burnell, Charles Edward
29, High Street, Shepton Mallet.
Feb. 28, 1913. Burns, Dr. Xesbitt, M.B., B.A., F.R.S.E.
" The Lodge," Highbridge, Somerset.
April 20, 1906. Burrell, T. Leonard
20, Upper Homsey Rise, Islington, N.
Feb. 19, 1904. Burton, James (Hon. Sec),
8, Somali Road, West Hampstead, N.W.
Jan. 24, 1911. Butcher, Thomas William, M.B., CM.,
F.R.M.S.
3, Clifton Street, Blackpool.
Feb. 19, 1904. Butterworth, Arthur Cyrus, F.R.M.S.
Glanville, Crowstone Road, Westcliff-on*
Sea.
April 15, 1904. Caffyn, Charles Henry,
32, Falkland Road, Homsey, N.
June 18, 1897. Campbell, Colney
47, Selborne Road, Southgate, N.
Mar. 16, 1906. Capell, Bruce John, F.R.M.S.
10, Castelnau, Barnes, S.W.
Mar. 28, 1914. Carlile, E.
28, Chatsworth Road, Croydon.
vm
Date of Election.
Jan. 20, 1905. Carrington, John /
P.O. Box 48, East London, South
Africa.
May 24, 1910. Carruthers, Ferdinand Gilbert
10, Addison Road, Bedford Park, W.
Jan. 25, 1910. Carter, John Arthur
6, Temple Road, Stowmarket.
June 17, 1892. Chaloner, G., F.C.S.
South Street, Colyton, S.O., Axminster.
Mar. 17, 1905. Chapman, David Leighton
100, Tooley Street, S.E.
June 28, 1910. Charlton, Alfred Edward
13, Parkhurst Road, Camden Road, N.
Oct. 26, 1909. Cheavin, Harold Squire, F.R.M.S.^
70, Somerset Road, Hudders field.
April 22, 1913. Cheshire, Frederic John, F.R.M.S.
23, Carson Road, Dulwich, S.E.
Mar. 22, 1878. Chester, The Very Rev. the Dean of
The Deanery, Chester.
Dec. 18, 1896. Chipps, F. W.
201, Castelnau, Barnes, S.W.
Jan. 20, 1905. Christie, John, F.R.M.S.
Henleigh, Kingston Hill, Surrey.
May 18, 1906. Churchouse, G.
30, Natal Road, Bowes Park, N.
Mar. 17, 1905. Clemence, Walter
Farringford, Walton-on-Thames.
Jan. 27, 1914. Clibborn, Lt.-Col. John
87, Victoria Street, S.W.
Oct. 18, 1907. Coldwells, William Henry
Redcote, Shirley Road, Wallington.
Jan. 28, 1913. Coles, Alfred C, M.D., D.Sc, F.R.S.E.
" York House,'" Poole Road, Bourne-
mouth.
Mar. 5, 1909. Collier, Oswald
The Hermitage, Snaresbrook.
Nov. 16, 1906. Collins, Brenton Robie, M.A.
Gorsebrook, Tunbridge Wells, Kent.
Oct. 21, 1904. Conrady, Alexander Eugen, F.R.A.S.
23, Flanchford Road, Stamford Brookt W.
IX
Date of Election.
Mar. 25, 1913. Cook, John Thomas
106, Thurlow Park Road, Dulwich,
S.E.
Nov. 26, 1912. Coon, Joseph May
" Morwenna" St. Austell.
April 20, 1906. Couch, Robert Percy
Jan. 18, 1901. Cox, Thomas N.
104, Tressillian Road, Brockley, S.E.
Jan. 15, 1904. Cox, William
" The Pound," Ling field, Surrey.
June 19, 1903. Coxhead, G. W.
5a, Springfield Gardens, Upper Clapton,
N.E.
Jan. 25, 1910. Crabtree, James Fox, B.A.
40, Brazennose Street, Manchester.
Dec. 20, 1901. Craig, Thomas, F.R.M.S.
26, Selkirk Avenue, Montreal, Canada.
Nov. 25, 1913. Creese, Edward J. E., F.Z.S., F.R.M.S.
29, Cornford Grove, Balham, S.W.
Nov. 21, 1902. Cressey, Dr. G. H.
Oak Manor, Tonbridge.
Aug. 28, 1868. Crisp, Sir Frank, LL.B., Y.P.L.S., B.A.,
F.R.M.S., F.G.S., F.Z.S.,
5, Lansdowne Road, Notting Hill, IV.
Mar. 20, 1908. Croger, Frank Clifford
114, Wood Street, E.G.
Nov. 16, 1906. Crosbie, Walter
Kenilworth, Lyonsdoivn Avenue, New
Bar net.
Jan. 25, 1910. Cross, Edward
Feb. 16, 1900. Crossland, R, E., A.R.I.B.A.
10, Serjeant's Inn, Fleet Street, E.G.
Mar. 16, 1894. Culshaw, Rev. George H., M.A.
The Rectory, Iver Heath, Bucks.
June 25, 1880. Curties, C. Lees, F.R.M.S.
244, High Holborn, W.G.
Jan. 16, 1903. Curties, C. L., jun.
244, High Holborn, W.G.
May 18, 1906. Cuzner, Edgar, F.R.M.S.
36, Trothy Road, Bermondsey, S.E.
X
Date of Election.
Nov. 18, 1904. Dade, Willoughby Dreyer
13, Glendinning Avenue, Weymouth.
Jan. 17, 1908. Dallas, Charles Caldwell, F.R.G.S., F.Z.S.
Eastley Wootion, New Milton, Hants.
Dec. 21, 1906. Darlaston, Herbert William Hutton
31, Freer Road, Birchfield, Birmingham.
Feb. 28, 1911. Davidson, John
29, Federation Road, Abbey Wood,
Kent.
Nov. 22, 1910. Davidson, Rev. Martin, M.A., B.Sc., F.R.A.S.
56, Hudson's Road, Canning Town, E.
June 16, 1905. Davies, Daniel, F.R.M.S.
12, Eliot Hill, BlacJcheath, S.E.
April 28, 1911. Davies, Daniel Arthur
12, Eliot Hill, BlacJcheath, S.E.
Jan. 19, 1906. Davies, Perceval Eckton
Abbeydale, Marmora, Road, Honor Oak,
S.E.
June 24, 1913. Dean, Frank
1, Langham Street, Portland Place, W.
May 17, 1901. Deeley, George P.
Moushall, Amblecote, Brierley Hill, Staf-
fordshire.
April 19, 1895. Delcomyn, Theo. A., F.R.M.S.
" Feldheim," Wimbledon Common, S.W~
Jan. 23, 1912. Dendy, Arthur, D.Sc, F.R.S. (President)
Vale Lodge, Hampstead Heath, N.W.
Nov. 17, 1893. Dennis, A. W.
56, Romney Buildings, MilbanJc, S.W.
Mar. 22, 1889. Dick, J.
Milber, Victoria Road, Mill Hill, N.W.
Feb. 15, 1907. Dilks, Arthur Charles, B.Sc.
Tardebigge, Bromsgrove.
June 24, 1913. Dinn, Harold H.
72, Elmwood Road, Heme Hill, S.E.
June 4, 1909. Dixon, Arthur L.
35, North Hill, Highgate, N.
June 17, 1892. Dixon-Nuttall, F. R., F.R.M.S.
" Ingleholme," Eccleston Park, near
Prescot, Lancashire.
XI
Date of Election.
Nov. 25, 1913. Dobell, Henry
74, Babbacombe Boad, Bromley, Kent.
Feb. 22, 1910. Doughten, William S.
415, Bace Street, Philadelphia, Pa.y
U.S.A.
Oct, 25, 1910. Douglas, William
Grafton House, Berkhamsted, Herts.
Oct. 24, 1911. Downing, Owen Walter
23, Glenhouse Boad, Eltham, Kent.
Mar. 17, 1899. Downs, Arthur
2, Ulverston Boad, W althamstow , E.
Nov. 23, 1909. Draper, Bernard M.
9, Pitt Street, Kensington, W.
May 17, 1907. Drinkwater, Jesse, F.R.M.S.
St. Margaret's, Stanley Gardens, Wal-
lington.
Nov. 15, 1901. Druett, C. R.
330, TJxbridqe Boad, W.
Dec. 28, 1909. Dumat, Frank C.
Feb. 22, 1910. Dunstall, George Kirkman, F.R.M.S.
82, Darenth Boad, Stamford Hill, N.
Feb. 25, 1913. Durrad, John Wm, F.R.A.S.
350, Fosse Boad North, Leicester.
June 19, 1891. Earland, Arthur, F.R.M.S.
34, Granville Boad, Watford.
May 15, 1908. East, John Holtham
75, Moorland Boad, Weston-super-Mare,
Sept, 25, 1868. Eddy, J. R., F.R.M.S., F.G.S.
The Grange, Carleton, Skipton, Yorkshire.
April 22, 1913. Edwards, Henry
22, Carnarvon Boad, Beading.
Oct. 22, 1912. Edwardes, Seabury
Pegu, Lower Burma.
Feb. 21, 1902. Edwards, Thomas Jarvis
9, St. Lawrence Boad, Brixton, S.W.
Oct. 22, 1912. Elliott, Wm.
97, Devonport Boad, Shepherd's Bush, If.
Xll
Date of Election.
Mar. 22, 19L0. Ellis, William Neale
The ' Pharmacy " Appledore, Devon.
Nov. 28, 1911. Emsley, Harold Percy
31, Victoria Road, Wood Green, N.
Mar. 24, 1914. Engelhardt, Conrad Wm.
6, Shaftesbury Villas, Kensington, W .
Feb. 28, 1879. Epps, Hahnemann
95, Upper Tulse Hill, Brixton, S.W.
Dec. 20, 1907. Evans, Benjamin
162, Batter sea Bridge Road, S.W.
Nov. 17, 1905. Evans, Morris B.
33, Lady Margaret Road, Southall,
Middlesex.
Dec. 21, 1906. Fawcett, Henry Hargreave
Thomcombe, near Chard, Somerset.
June 24, 1913. Fendich, Ernest Alfred
22, Finedon Road, Wellingborough,
Northants.
June 16, 1893. Filer, Frank E.
35, Dancroft Road, Heme Hill, S.E.
Feb. 19, 1904. Finlayson, Daniel
" Red/em," Pellatt Grove, Wood Green, N.
Feb. 24, 1914. Finlayson, Raymond
22, Pellatt Grove, Wood Green, N.
June 19, 1908. Flamank, Sydney W.
Church House, Dean's Yard, West-
minster, S.W.
Nov. 23, 1888. Flood, W. C.
119, Highbury Hill, N.
Mar. 25, 1913. Ford-Fone, W. Edwin
146, Palmers Road, New Southgate.
June 23, 1871. Freeman, H. E.
Walcot, Limes Avenue, New Southgate, N .
Dec. 16, 1898. French, Archibald J.
57, Ermine Road, Lewisham, S.E.
Jan. 18, 1907. Fuelling, George Ernest
195, High Road, Streatham, S.W.
Feb. 22, 1910. Fuller, Frederick Charles
9, Goldington Road, Bedford.
Xlll
Date of Election.
Nov. 21, 1902. Fuller, William
24, Coleford Road, Alma Road, Wands-
worth, S.W.
May 15, 1903. Gabb, G. H., F.C.S.
83, Cray ford Road, Tufnell Park, N.
Nov. 25, 1913. Gamman, Robt.
13, Park Road, High Barnet.
Feb. 27, 1912. Gammon, Geo. Edwd.
6, Mackintosh Place, Roath, Cardiff.
Dec. 15, 1905. Gardner, Edward Lewis
1, Craven Road, Harlesden, N.W.
Jan. 20, 1899. Gardner, William, F.R.M.S.
292, Holloway Road, N .
Dec. 16, 1904. Garnett, Theodore, M.A. Oxon
South Bank, Grassendale, Liverpool,
Jan. 27, 1914. Gee, Harry Arthur
20, Buckler sbury , B.C.
Mar. 24, 1914. Gingell, Leonard Ralph
10, Moring Road, Tooting, S.W.
May 17, 1901. Gladding, Harold
Nov. 22, 1910. Gladstone, Reginald J., M.D.
22, Regent's Park Terrace, N.W.
Mar. 22, 1910. Gonville, Cyril H. K.
" Milton," Queen's Road, Buckhurst Hill?
N.
Feb. 24, 1914. Gooding, Alfred Charles
53, Park Road, Battersea, S.W.
Dec. 28, 1909. Gooding, Henry Cornish
Stowmarket, Suffolk.
April 2, 1909. Gordon, Fred William, F.R.M.S.
" Graylands," Augustus Road, Wimble-
don Park, S.W.
Feb. 22, 1910. Gordon, John WT.
113, Broadhurst Gardens, Hampstead,
N. W.
Nov. 15, 1907. Gray, W.
23, Ramsden Road, Balham, S.W.
Jan. 25, 1910. Green, Frederick N.
40, Lombard Street, E.C.
XIV
Date of Election.
Jan. 16, 1903. Green, H. 0.
4, Leamington Gardens, Seven Kings.
Nov. 18, 1898. Grocock, L. 0.
May 24, 1910. Grundy, James, F.R.M.S.
" Ruislip" Teignmouih Road, Crickle-
wood, N.W.
June 25,- 1912. Gurney, Joseph
Doivns Farm, Pinner S.O., Middlesex.
Feb. 19, 1904. Gurney, Robert
Ingham Old Hall, Stalham, Norfolk.
Nov. 28, 1911. Guye, Dr. Paul
12, Rue de Candolle, Geneva, Switzer-
land.
Feb. 25, 1913. Hall, Rd.
4, Inglewood Mansions, West End Lane,
Hampstead, N.W.
Sept. 28, 1888. Hall, T. F.
45, Princes Gate, S.W.
Feb. 22, 1910. Hammond, Alfred Gauntlett
101, Melody Road, Wandsworth, S.W.
Jan. 25, 1910. Hammond, Arthur Rashdall
15, Genoa Road, Anerley, S.E.
April 26, 1910. Hammond, Leonard Frank
22, Mercers Road, N.
Oct. 22, 1886. Hampton, W.
The Manor House, Weston, Staffordshire.
Nov. 26, 1912. Hardman, Wm, J.P.
" Fernleigh," Bispham, near Blackpool.
Nov. 22, 1910. Harris, A. Wellesley, M.R.C.S., etc.
" Alnwick," Berlin Road, Caiford, S.E.
May 19, 1905. Harris, Charles Poulet, M.I)., M.R.C.S.,
L.R.C.P., F.R.M.S.
98, Lower Addiscombe Road, Croydon.
Jan. 27, 1914. Harris, Leslie Edwin
19, Cheriton Square, Balham, S.W.
Dec. 21. 1906. Hasslacher, Charles John
3, Kensington Park Gardens, W.
Mar. 28, 1879. Hawkins, C. E.
23, Dalebury Road, Upper Tooting, S.W .
Date of Election.
Nov. 26, 1912. Hayward, Leslie Chas.
68, Queens Road, Bay stealer, W.
Feb. 15, 1901. Headley, F. W.
Haileybury College, Hertford.
Jan. 19, 1906. Heath, Charles Emanuel, F.R.M.S.
178, Loughboro' Road, Brixton, S.W.
Feb. 5, 1909. Hebdon, William
181, Breakspears Road, Brockley, S.E.
April 20, 1906. Herbert, Robert Henry
32, Fairmead Road, Holloway, N.
Feb. 21, 1908. Heron-Allen, Edward, F.L.S., F.G.S.,
F.R.M.S., F.R.Met.S., F.Z.S.
33, Hamilton Terrace, N.W., and Large
Acres, Selsey Bill, Sussex.
Dec. 20, 1901. Hicks, Frederick H.
8, Belmont Road, Wallington, Surrey.
Dec. 22, 1910. Higginson, George Neale
42, Bartholomew Road, Camden Town,
N.W.
Feb. 17, 1899. Hill, Edward J.
Darnlee, Melrose, N.B.
Nov. 26, 1912. Hill, Wm, F.G.S.
" The Maples" Hitchin.
Nov. 15, 1895. Hilton, A. E.
1, Highwood Avenue, North Finchley,
N.
May 15, 1908. Hiscott, Thomas Henry, F.R.M.S.
16, Vioodville Road, Ealing, W.
May 27, 1913. Hoare, Stanley
" Baronscourt," The Bishops Avenue,
N.
Nov. 16, 1906. Hocking, William John
Royal Mint, E.
Dec. 15, 1893. Holder, J. T.
114, Pepys Road, Nevj Cross, S.E.
Feb. 26, 1875. Holford, Christopher
5, Northumberland Avenue, Upper Rich-
mond Road, Putney, S.W.
Dec. 20, 1907. Holmes, Frederick
217, Franciscan Road, Tooting, S.W.
XVI
Date of Election.
June 25, 1912. Hook, Gerald Francis
9, Barrowgate Road, Chiswick, W.
May 27, 1913. Hook, Reginald Vincent
9, Barrowgate Road, Chiswick, W.
Jan. 15, 1904. Hopkinson, John, F.L.S., F.G.S., F.R.M.S.
Weetwood, Watford.
Oct. 26, 1866. Horncastle, Henry
' Lindisaye," Woodham Road, Woking.
April 15, 1898. Hounsome, John
21, Edith Road, Plashet Grove, East
Ham, E.
Dec. 4, 1908. Howard, George
Sitwell Vale, Moorgate, Rotherham, Yorks.
Oct. 19, 1894. Howard, R. N., M.R.C.S., F.R.M.S.
The Cape Copper Co., Ookiep, Port
Nolloth, Namaqualand, Cape Colony,
South Africa.
June 25, 1912. Ho worth, Geo. Franklin Wise
55, Grovelands Road, Palmer's Green, N.
Oct. 19, 1894. Hughes, F.
Wallfield, Reigate.
May 28, 1886. Hughes, W.
32, Heathland Road, Stoke Newington, N.
Nov. 23, 1909. Huish, Charles Henry, F.R.M.S.
23, Champion Grove, Grove Lane, S.E.
June 4, 1909. Hunter, John E.
" Strathblane," Park Road, Wallington.
Dec. 20, 1901. Hurrell, Harry Edward
25, Regent Street, Great Yarmouth.
Feb. 25, 1913. Hutchin, Chas. Duncan
c/o Meredith & Drew, Ltd., High Street,
Shadwell, E.
May 24, 1867. Ingpen, J. E., F.R.M.S.
21, Wrotham Road, Broadstairs.
Feb. 16, 1906. Inwards, Richard, F.R.A.S.
6, Croftdown Road, Highgate Road, N. W.
Feb. 28, 1911. Jacob, Hugh Frederick Dawson, M.I.E.E.
c/o Jessop & Co., Ltd., 93, Clive Street,
Calcutta.
XV11
Date of Election.
Feb. 27, 1912. Jacobs, Reginald
24, Glenmore Road, Belsize Park, N.W.
April 26, 1910. Jervis, Rev. Edward S.
St. Peter's Vicarage, Streatham, S.W.
Nov. 22, 1910. Jewell, Henry
152, Leathwaite Road, Clapham Common,
S.W.
Nov. 17, 1905. Jones, Arthur Morley
11, Eaton Rise, Ealing, W.
April 26, 1910. Jones, George Fisher
Devonshire House, Osterley Park Road,
Southall, W.
Jan. 18, 1907. Jones, Rev. Robert Francis
28, Douglas Road, Canonbury,N.
Feb. 22, 1910. Jones, William Llewellyn
Manley Knoll, Helsby, Cheshire.
Feb. 22, 1910. Joshua, Edward Cecil
St. James's Buildings, William Street,
Melbourne, Victoria.
Nov. 17, 1905. Karleese, Benjamin
The Dell, Barnt Green, Worcestershire.
May 23, 1873. Karop, G. C, M.R.C.S., F.R.M.S., etc.
Inniscorig, Belting e Road, Heme Bay.
Feb. 25, 1913. Kaufmann, James C, LL.D.
49, Queen Street, Melbourne.
June 21, 1907. Kemp, Francis H. N. C.
15, Vernon Road, Homsey, N.
July 25, 1884. Kern, J. J.
63, Queens Road, Beckenham, Kent.
Nov. 18, 1904. Kew, H. Wallis
3, Hemdon Road, Wandsworth, S.W.
May 17, 1901. Kirkman, Hon. Thomas, M.L.C., F.R.M.S.
Croftlands, Esperanza, Natal.
May 19, 1905. Kitchin, Joseph, FJl.M.S.
" Ingleneuk," 14, Brackley Road, Becken-
ham, Kent.
Mar. 22, 1889. Klein, S. T., F.R.A.S., F.L.S., F.R.M.S.
" Hatherloiv," Raglan Road, Reigate.
b
XV111
Date of Election.
Dec. 28, 1909. Knox, Sydney W.
61, Cambridge Street, Hyde Park, W.
Mar. 24, 1914. Koch Victor, M.E.
43, Elgin Avenue, Maida Vale, W.
Feb. 17, 1905. Lambert, Charles Alexander
Bank of New South Wales, Waricick,
Queensland.
Jan. 18, 1907. Larkin, Thomas Gaisford
29, Thornlaw Road, West Norwood, S.E.
Feb. 27, 1912. Laverach, Clyvie Cordukes
Br ought on Rise, Malton, Yorks.
June 17, 1904. Lawrence, Frederick George
c/o Lionel Samson & Son, Cliff Street,
Fremantle, West Australia.
Feb. 25, 1913. Lawrence, Harry John
7, Norman Road, South Wimbledon, S.W.
April 26, 1910. Lawrence, William John
21, Cambridge Road, Lee, S.E.
Mar. 16, 1900. Lawson, Peter
" Jesmond," Nella Road, Fulham Palace
Road, S.W.
Jan. 1, 1909. Leadbeater, Herbert C.
81, Elborough Street, Southfields, S.W.
Jan. 20, 1905. Lees, Rev. Frederick Clare,
45, Cavendish Road, Sutton, Surrey.
Nov. 21, 1902. Leonard, Edward
14, Fairview Road, Oxton, Birkenhead.
Nov. 17, 1905. Levett, Rev. Robert Kennedy, F.R.M.S.
The Junior School, Bradfield College,
Reading, Berks.
Jan. 17, 1908. Levin, Arthur Everard
" The Croft;' Bickley, Kent.
Feb. 22, 1910. Lewis, Frederic Henry
" Ashmore," King's Avenue, Clapham
Park, S.W.
April 27, 1866. Lewis, R, T., F.R.M.S. {Hon. Reporter)
41, The Park, Ealing, W.
Nov. 25, 1913. Liddon, Capt, Matthew Robert
12, Kensington Court, W.
XIX
Date of Election.
June 26, 1868. Lindley, W. H., jun.
29,BlittersdorffsPlatz,Frankfort-on-Main.
Mar. 24, 1914. Lloyd, Francis Wm. y
85, Gracechurch Street, E.G.
Dec. 23, 1913. Lock, Thos. Benjn.
78, Riggindale Road, Streatham, S.W.
Jan. 18, 1907. Lyon, Massey, F.R.M.S.
c/o Messrs. Coutts, 440, Strand, W.C.
May 25, 1883. Mainland, G. E., F.R.M.S.
14, The Norton, Tenby, South Wales.
Nov. 26, 1912. Mardon, Daniel Arthur
" Emscote," Bishops Stortford.
June 17, 1898. Marks, Kaufmann J., F.R.M.S.
4, Woodchurch Road, West Hampstead,
N. W.
Jan. 24, 1911. Marsh, George Robertson, M.A.
Mallards Close, Twyford, near Win-
chester, Hants.
Feb. 15, 1895. Marshall, William John, F.R.M.S.
20, Emlyn Road, Shepherd's Bush, W .
May 18, 1906. Martin, William
" Kethlen," Burgh Heath, Epsom, Surrey.
Nov. 28, 1911. Martin, Wm. Julius
55, Breakspears Road, Brockley, S.E.
Nov. 18, 1898. Massee, G., F.L.S.
Royal Gardens, Kew.
Jan. 28, 1913. Mavor, Hilary
" Rookivood," Ingatestone, Essex.
Jan. 15, 1892. Maw, W. H., F.R.M.S., F.R.A.S.
18, Addison Road, Kensington, W .
Mar. 28, 1911. Maxwell, Edward Kelly, B.A.
H.M. Patent Office, W.C.
April 23, 1912. Mead, Arthur
May 19, 1893. Merlin, A. A. C. Eliot, F.R.M.S.
British Consulate, Volo, Greece.
Oct. 18, 1907. Mestayer, Richard L., M.I.C.E., F.R.M.S.
Lambton Quay, Wellington, New Zea-
land.
XX
Date of Election.
Mar. 26, 1912. Metealf, John
St. Bede's, Hermon Hill, Woodford, E.
July 27, 1877. Michael, A. D., F.L.S., F.Z.S., F.R.M.S.
The Warren, Studland, near Wareham,
Dorset.
July 7, 1865. Millett, F. W., F.G.S., F.R.M.S.
Eniscoe, Brixham, Devon.
Feb. 25, 1913. Mills, Fdk. Wm, F.R.M.S.
Thornleigh Edgerton, Huddersfield.
Jan. 20, 1905. Milne, William
Uitenhage, Cape Colony, South Africa.
Oct. 18, 1907. Minchin, Edward Alfred, M.A., Ph.D., F.R.S.,
(Vice-President)
53, Cheyne Court, Royal Hospital Road,
Chelsea, S.W.
Oct. 18, 1901. Moore, Harry, F.R.M.S.
12, Whiston Grove, Moorgate, RotJierham,
Yorks.
July 26, 1878. Morland, Henry
Cranford, near Hounslow.
Oct. 25, 1910. Morris, Charles Barham
Waitaki Pharmacy, Thames Street, Oa~
maru, N.Z.
June 25, 1912. Morris, Jesse Crawford
Harrisville, Harrison County, Ohio, U.S.A.
June 4, 1909. Mortimer, Hugh Hamilton
20, Birchin Lane, E.C.
Jan. 16, 1891. Muiron, C.
49, Chatsworth Road, Brondesbury, N.W.
Dec. 23, 1913. Mumford, Frank Septimus
Belmont, Doncaster. *
Nov. 22, 1910. Mummery, J. Howard, M.R.C.S.
Islips Manor, Northolt, Middlesex.
June 16, 1905. Myles, James Cellars
53, Carlyle Road, Manor Park, S. Essex.
Jan. 27, 1914. Nail, Rev. Geo. Herbert
18, Deans Yard, Westminster, S.W.
Mar. 24, 1876. Nelson, E. M., F.R.M.S.
Beckington, Bath.
XXI
Date of Election.
May 16, 1902. Nevill, Rev. T. J., F.R.M.S.
2, Grange Road, Eastbourne.
Feb. 15, 1907. Newman, Charles Arnold
Oundle, Northants.
May 27, 1913. Newniarch, Edgar Ribton
4, The Drive, Walthamstow, N.E.
Jan. 26, 1872. Newton, E. T., F.R.S., F.G.S.
Florence House, 13, Willow Bridge Road,
Canonbury, N.
Jan. 17, 1908. Nicholson, Alfred
7, Belton Road, Sidcup.
Dec. 23, 1913. North, Jas. Herbert
11, Parliament Hill, Hampstead,
N.W.
Nov. 28, 1911. Nutt, Hy. Francis
51, Gurdon Road, Charlton, S.E.
Feb. 25, 1913. Oatley, Wm.
Badcox, Frome
Feb. 16, 1900. O'Donohoe, T. A.
8, Myrtle Road, Acton, W.
Jan. 24, 1879. Offord, J. M., F.R.M.S.
3, Cleveland Gardens, West Ealing, W.
Dec. 22, 1876. Ogilvy, C. P., F.L.S.
Sizewell House, Leiston, near Saxmund-
ham, Suffolk.
May 17, 1907. Ogilvy, J. Wilson, F.R.M.S.
18, Bloomsbury Square, W.C.
Nov. 15, 1907. Oke, Alfred William, B.A., LL.M.
32, Denmark Villas, Hove.
Nov. 18, 1892. Orfeur, Frank, F.R.M.S.
91, Effra Road, Brixton, S.W.
April 23, 1912. Owen, Wm. Hy.
19, Home Park Road, Wimbledon.
Dec. 27, 1867. Oxley, Frederick, F.R.M.S.
c/o A. E. Linton, Esq., Box 9, P.O.,
Nairobi, British East Africa,
Dec. 18, 1903. Oxley, F. J., M.R.C.S.
1, Dock Street, E.
XX11
Date of Election.
Feb. 27, 1912. Palmer, Hy., J.P., F.R.G.S.
Monks Holme, Corbridge-on-Tyne.
Nov. 25, 1913. Panichelli, Frank
7, Rowan Road, Hammersmith, W.
April 10, 1910. Parfitt, Edward William
7, Gatcombe Road, Tujnell Park, N.
Feb. 25, 1913. Parrott, Fdk. Wm.
The Downs, Bowden, Cheshire.
Oct. 27, 1871. Parsons, F. A., F.R.M.S.
15, Osborne Road Finsbury Park, N.
Dec. 16, 1904. Patterson, George
20, Madrid Road, Castlenau, Barnes,
S.W.
July 23, 1886. Paul, R.
" Holmbush" Cyprus Road, Exmouth,.
Devon.
Jan. 18, 1901. Paulson, Robert, F.L.S., F.R.M.S.
" Glenroy," Cecil Park, Pinner, Middle-
sex.
May 24, 1867. Pearson, John
40, Maida Vale, W.
May 23, 1911. Pells, Cyril E.,
May 20, 1904. Perks, Frederick John (Hon. Treasurer)
48, Grove Park, Denmark Hill, S.E.
Jan. 18, 1907. Perry, Francis Gough
2, The Cloisters, Gordon Square, W.C.
Mar. 17, 1905. Phipps, William Joseph
132, Pinner Road, Oxhey, Herts.
Feb. 20, 1903. Pilcher, Charles Frederick
Nov. 15, 1895. Pillischer, J., F.R.M.S.
88, New Bond Street, W.
April 25, 1910. Pinchin, Ernest Alfred, B.Sc,
4, Gleneldon Road, Streatham, S.W.
Nov. 26, 1912. Pitt, Edward
Madeley Ho., Gerrard's Cross, Bucks.
Nov. 19, 1897. Pittock, George Mayris, M.B., F.R.M.S.
Winton, Whitstable Road, Canterbury.
Jan. 15, 1904. Pledge, John H., F.R.M.S. {Hon. Assistant
Secretary)
72, Nibthwaite Road, Harrow.
XX111
Date of Election.
Nov. 23, 1883. Plowman, T.
Nystuen Lodge, Bycullah Park, Enfield.
Sept. 21, 1894. Pollard, Jonathan, F.R.M.S.
10, Porteus Road, Paddington Green, W.
May 18, 1900. Poser, M., F.R.M.S.
37-38, Hatton Garden, E.C.
June 21, 1895. Poulter, Christopher S.
Mount Lodge, Parkhurst Road, Bexley,
Kent.
Feb. 17, 1899. Powell, Arthur
28, Stafford Terrace, Kensington, W.
May 17, 1901. Powell, David, M.A., F.R.M.S.
Over strand, Grove Park Road, Chiswick, W.
July 7, 1865. Powell, Thomas H., F.R.M.S.
Emsdale, Greenham Road, Muswell Hill,
N.
Dec. 20, 1907. Pratt, John Edwin
6, Heath field Terrace, Seven Kings, Essex.
June 4, 1909. Pring, S. W.
" Sandhill, " Avondale Road, Newport,
Isle of Wight.
Xov. 26, 1912. Pulford, Herbert, M.A., etc.
The Winnats, Lowestoft Road, Gorleston-
on-Sea.
Feb. 28, 1911. Pullman, John
The Knollsea, Lilliput, Dorset.
Xov. 6, 1908. Quick, Albert Hedley
" Inverness," Malvern Road, Thornton
Heath.
Jan. 18, 1901. Radley, Percy E., F.R.M.S.
30, Foxgrove Road, Beckenham, Kent.
Xov. 25, 1913. Ramsay, Ernest Wm.
14, Whiteley Road, Upper Norwood, S.E.
April 22, 1913. Rawson, Col. Herbert Edward, C.B.
Home Close, Heronsgate, Herts.
Xov. 16, 1906. Reid, Duncan J., M.B., CM.
20, Blakesley Avenue, Ealing.
Mar. 20, 1896. Rheinberg, Julius, F.R.M.S.
23, The Avenue, Brondesbury Park, N.W.
XXIV
Date of Election.
Sept. 18, 1891. Richards, F. W.
212, Notre Dame Street West, Montreal,
Canada.
Oct. 2, 1908. Richards, William
3, Favart Road, Fulham, 8. W.
Jan. 18, 1901. Richardson, John
28, Beaumont Avenue, Richmond, Surrey.
Nov. 6, 1908. Rink, Max
9, Cannon Place, Christchurch, H amp-
stead, N.W.
June 21, 1901. Robertson, Sir Helenus R., F.R.M.S.
Upton Grange, Chester.
Mar. 15, 1907. Robertson, James Alexander, F.R.M.S.
Lune View, Fleetwood.
April 28, 1914. Robotham Fras. Edward
48, Lillieshall Road, Clapham, S.W.
JNov. 16, 1900. Rogers, G. H. J., F.R.M.S.
55, King Street, Maidstone.
June 4, 1909. Rolph, Frank
Harts Stables, Woodford Green, E.
Jan. 25, 1884. Rosseter, T. B., F.R.M.S.
East Kent Club, Canterbury.
Jan. 26, 1883. Rousselet, Charles F. (Vice-President and
Hon. Secretary for Foreign Correspondence) ,
Curator R.M.S.
Fir Island, Mill Hill, N.W.
Nov. 26, 1912. Row, Rd. Wm. Harold
36, Lexham Gardens, Kensington, S. W.
Nov. 18, 1904. Rowley, Frederick Richard, F.R.M.S.
8, Pinhoe Road, Heavitree, Exeter.
April 27, 1888. Russell, J.
16, Blacket Place, Newington, Edinburgh.
Jan. 23, 1912. Ryan, Ernest K. W.
5, Rossdale Road, Putney, S.W.
Mar. 24, 1914. St. George, Harry A.
112, Albany Street, Regent's Park, N.W.
Nov. 21, 1902. Sanderson, R. Z.
26, Baronsfield Road, St. Margaret's, E,
Twickenham, Middlesex.
XXV
Date ol Election.
Dec. 23, 1913. Saunders, Reginald Arthur
10, Regent's Park Road, N.W.
April 2, 1909. Saxton, Thomas R., A.M.I.C.E., F.R.M.S.
43, East Bank, Stamford Hill, N.
Xov. 28, 1911. Schmerl, Augustus
34, St. Gabriel's Road, Cricklewood,
N.W.
June 20, 1890. Scourfield, D. J., F.Z.S., F.R.M.S. {Vice-
President)
63, Queen's Road, Leytonstone, E.
May 20, 1898. Sears, Robert S. W. -
1, Lisson Grove, N.W.
Jan. 27, 1914. Shelley, G. H.
51, Champion Grove, Denmark Hill, S.E.
Xov. 25, 1913. Shepherd, Benjamin
Fir Cottage, Oak Lane, Bounds Green, N.
Dec. 28, 1909. Shephard, John
Clark Street, South Melbourne, Victoria.
May 26, 1876. Shepheard, Thomas, F.R.M.S.
Kingsley, Bournemouth West.
June 21, 1907. Sheppard, Alfred William, F.Z.S., F.R.M.S,
{Hon. Editor)
1, Vernon Chambers, W.C.
Jan. 28, 1913. Sheppard, Eclwd. Jas., F.R.M.S.
137, Kenninglon Road, S.E.
Mar. 25, 1913. Shuckard, David Hy.
14, Walerand Road, Leivisham, S.E.
Feb. 28, 1911. Sidebottom, Henry
" Woodstock,'' Syddal Park, BramhaU,
Cheshire.
June 19, 1896. Sidwell, Clarence J. H., F.R.M.S. {Hon.
Curator)
46, Ashbourne Grove, Duhvich, S.E.
Feb. 22, 1910. Simpson, Norman Douglas
Carlton Mincott Vicarage, Thirsk,
Yorks.
Oct. 26, 1903. Skorikow, Alexander Stepanovic
Musee Zoologique de VAcademie lin-
periale des Sciences, St. Petersburg,
Russia.
XXVI
Date of Election.
Oct. 21, 1904. Smith, Arthur Edgar
" Helios," 71, Fox Lane, Palmer's Green,
N.
Mar. 25, 1870. Smith, F. L.
3, Grecian Cottages, Crown Hill, Norwood,
S.E.
Mar. 17, 1899. Smith, Frank P.
2, King's Villas, Chase Road, Southgate.
Mar. 17, 1905. Smith, Frederick
13, Rye Hill Park, Peckham Rye, S.E.
Nov. 18, 1898. Smith, Thomas J., F.R.M.S.
c/o W. Watson & Sons, 313, High Hol~
born, W.C.
Jan. 15, 1892. Soar, C. D., F.L.S., F.R.M.S.
37, Dryburgh Road, Putney, S.W.
April 21, 1899. Spitta, Edmund J., L.R.C.P., M.R.C.S.,
F.R.A.S., F.R.M.S. {Vice-President)
41, Ventnor Villas, Hove, Brighton.
April 21, 1899. Spitta, Harold R, D., M.D., M.R.C.S.,
D.R.C.P., D.P.H.
12, Bolton Street, May fair, W.
Jan. 15, 1904. Sprague, T. B., LL.D.
29, Buckingham Terrace, Edinburgh.
Dec. 23, 1913. Sprenger, Hy. Fdk. Wm.
64, Hallam Street, Portland Place, W.
Jan. 28, 1913. Spry, Lt. Robt., R.N., F.R.M.S.
83, Mount Gold Road, Plymouth.
Jan. 18, 1907. Stahl, Arthur
11, Scotts Avenue, Shortlands, Kent.
Nov. 16, 1906. Stephens, Samuel Phillips
15, Green Street, Kimberley, Cape Colony.
Nov. 27, 1885. Stevenson, G. T.
Ravenscourt, Haling Park Road, South
Croydon.
June 18, 1897. Still, Arthur L.
Roslyn, Dower Avenue, Wallington.
Nov. 16, 1894. Stokes, William B.
212, Notre Dame Street, West Montreal.
Dec. 15, 1893. Sturt, Gerald
' Lismore," Cavendish Road, Weybridge.
xxvn
Date of Election.
Dec. 17, 1875. Swift, M. J., F.R.M.S.
6, Aylestone Avenue, Brondesbury, N .W .
Nov. 28, 1879. Tasker, J. G.
30, Junction Road, Upper Holloway, N.
Oct, 16, 1896. Taverner, Henry, F.R.M.S.
319, Seven Sisters Road, Finsbury Park,
N.
May 24, 1910. Taylor, Charles Ernest
178, Uxbridge Road, West Ealing.
Feb. 17, 1905. Taylor, Thomas George
Ballaclague, Ellington Park Road, Rams-
gate.
Dec. 22, 1865. Terry, John
8, Hopton Road, Coventry Park, Streat-
ham, S.W.
Feb. 28, 1911. Thomas, Edwin Harvey
Mar. 26, 1912. Tibbie, Bertie Wallace
27, St. Paul's Road, Canonbury, N.
June 24, 1913. Tierney, Clarence M. S., F.R.M.S.
10, Enmore Park, Norwood, S.E.
May 16, 1902. Tilling, George, F.R.M.S.
" Grasmere," Rydal Road, Streatham,
S.W.
Nov. 25, 1913. Tilling, Wm. Geo.
20, Streathbourne Road, Upper Tooting,
S.W.
Jan. 25, 1910. Todd, Charles Stephen
25, Hanover Road, Tottenham, N.
Feb. 27, 1912. Tomlinson, Edwd. Theodore
8, St. George's Square, S.W.
Nov. 26, 1912. Tonkin, Thos. S.
Bramley Avenue, Coulsdon, Surrey.
Dec. 21, 1894. Traviss, Will. R,
42, Winchester Avenue, Brondesbury,
I N. W.
Feb. 25, 1913. Trotman, Alex. Chas.
28, Gubyon Avenue, Heme Hill, S.E.
Mar. 5, 1909. Troughton, Henry George
3, New Court, Lincoln's Inn, W.C.
XXV111
Date of Election.
May 15, 1903. Tupman, Lt.-Col. G. Lyon, F.R.M.S.
College Road, Harrow.
June 17, 1892. Turner, C.
20, Minster Road, Crickleivood, N.W.
Feb. 25, 1913. Tyas, Rev. Vetranio
12, Felstead Road, Wanstead, N.E.
June 21, 1901. Tvrell, E. G. Harcourt
Park Rynie, Natal, S.A.
Mar. 16, 1906. Vogeler, Gustav
17, Philpot Lane, E.C.
Jan. 24, 1914. Walker, Arthur
306, South Lambeth Road, S.W.
July 25, 1873. Walker, J. S.
6, Warwick Road, Upper Clapton, N.E.
Nov. 22, 1910. Watts, Geo. W.
103, Haverstock Hill. N.W.
Dec. 21, 1900. Webster, Rev. T.
June 16, 1899. Wedeles, James, F.R.M.S.
231, Flinders Lane, Melbourne, Aus-
tralia.
May 28, 1912. Weiss, Robt,
7 & 8, Idol Lane, E.C.
Mar. 20, 1908. West, Joshua Cobbett
20, Millbrook Road, Brixton, S. W.
Feb. 25, 1876. Wheeler, George
64, Canonbury Park South, N.
Jan. 25, 1910. Whitehead, Henry, B.Sc. Lond.
Wadham House, Toynbee Hall, Com-
mercial Road, E.
Nov. 26, 1912. Whitteron, Fred.
Geelong, Victoria.
Dec. 4, 1908. Wilkins, Thomas Smith
Eversley, Uttoxeter.
Nov. 23, 1877. Williams, G. S.
Tor Hill, King sker swell, Devon..
Jan. 19, 1906. Wilson, Joseph, F.R.M.S.
Hillside, Avon Road, Upper Waliham
stow, Essex.
XXIX
Date of Election.
Feb. 27, 1912. Wood, Fredk. Geo.
161, Walworth Road, S.E.
Dec. 20, 1895. Wood, Walter J., F.R.M.S.
" Ernecroft," Abbey Road, Grimsby.
Nov. 16, 1894. Wooderson, Edwin
" Konigsfeld," 39, Dartmouth Road,
Brondesbury, N.W.
Mar. 15, 1907. Worssam, Cecil
17, Grafton Road, Bedford.
Jan. 18, 1907. Wright, Joseph Pepper
c'to Messrs. Davidson, Boules, Ld., 86,.
Wellington Street, West Toronto,
Canada.
Feb. 21, 1902. Wyatt, Edward
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